This is a working overview of Nuclear receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-01-07. Anything still debated is marked as such rather than presented as settled.
GW501516 acts as an agonist at the peroxisome proliferator-activated receptor delta, a nuclear receptor that regulates gene expression. Activation shifts transcription toward genes involved in fatty acid uptake, oxidation, and energy expenditure. The compound does not bind the androgen receptor and therefore differs from anabolic steroids and SARMs. In rodent models, this metabolic shift has been linked to increased running endurance and reduced fat accumulation. The exact downstream pathways in humans remain incompletely characterized.
Early clinical research explored GW501516 for lipid disorders, obesity, and diabetes. Some short-term human studies reported changes in HDL cholesterol, LDL cholesterol, and triglycerides. The development program was discontinued after rodent studies showed dose-dependent tumor formation in multiple tissues, including liver, bladder, stomach, and skin. These findings raised concerns about long-term cancer risk in humans. Because human exposure data are limited, the clinical significance of the rodent tumors remains uncertain.
Literature on cardarine often separates receptor pharmacology from toxicology. Mechanistic papers describe PPARδ activation and gene expression changes, while safety assessments focus on carcinogenicity and species differences. Questions remain about whether rodent tumors arise through PPARδ-dependent or off-target mechanisms. Another open area is how human metabolism and exposure compare with those in animal studies. Analytical methods such as liquid chromatography–mass spectrometry are used to confirm identity in biological and product samples.
Anti-doping laboratories identify GW501516 and related metabolites using liquid chromatography coupled with tandem mass spectrometry. Urine is the most common matrix, though blood and dried blood spots may also be analyzed. The method targets the parent compound and phase I and phase II metabolites, which extend the detection window. Because the substance is prohibited at all times, athletes can be tested outside competition. Detection limits and windows depend on the assay, sample type, and individual metabolism.
Cardarine is frequently described as a fat-burning or endurance-enhancing supplement, but these claims exceed the available evidence. The compound is not a hormone, steroid, or selective androgen receptor modulator. Research articles discuss it as a tool compound for studying PPARδ biology, while anti-doping literature focuses on its abuse and detection. Quality of unapproved products is uncertain, and independent analyses have found impurities or incorrect labeling. Open questions include whether human cancer risk resembles that seen in rodents and how often non-athletes use the substance.
Cardarine has no approved therapeutic indication and is not marketed as a medicine. The World Anti-Doping Agency lists GW501516 as a prohibited substance at all times, covering both in-competition and out-of-competition periods. National laws vary: some countries treat it as an unapproved drug subject to import controls, while others have specific restrictions on sale for human consumption. It is often sold as a research chemical, a label that does not imply safety or legality. Enforcement actions have targeted online vendors and shipments.
| Property | Value | Notes |
|---|---|---|
| Primary target | PPARδ | Nuclear receptor; not androgen receptor |
| Studied indications | Dyslipidemia; obesity; diabetes | Early clinical research; development discontinued |
| Rodent toxicity | Tumor formation in multiple tissues | Dose-dependent findings in some studies |
| Human approval | None | No approved therapeutic use |
| Typical analytical method | LC-MS/MS | Used for identity and quantification |
Cardarine is a common name for GW501516, an investigational compound developed in the 1990s for metabolic conditions. It acts as an agonist at peroxisome proliferator-activated receptor delta, a nuclear receptor involved in lipid and energy metabolism. The compound is frequently mislabeled as a selective androgen receptor modulator, or SARM, but its molecular target is different. GW501516 reached early clinical testing before development was discontinued. It has no approved therapeutic use in any country. The name cardarine is not a formal international nonproprietary name.
Regulatory treatment varies, but cardarine is not approved as a medicine. Sports authorities list GW501516 as a prohibited substance, and it is banned at all times under the World Anti-Doping Agency code. Many countries restrict sales for human consumption, while online vendors market it as a research chemical. Such products may lack purity data, and their actual contents can differ from the label. Purchasing or possessing cardarine may carry legal consequences depending on jurisdiction. The compound is not a dietary supplement ingredient in regulated markets.
Clinical development stopped after rodent studies showed tumors at multiple sites. Whether those findings predict human cancer risk remains an open question, but they led sponsors to discontinue programs. Human safety data are limited to small, short-term studies that were not designed to assess cancer risk. Reported effects in those studies included changes in blood lipids, but the evidence is insufficient for medical use. Long-term consequences of nonmedical use are not well characterized. Questions about dose, duration, and individual susceptibility remain unresolved.
GW501516 acts as a ligand for PPAR delta, a nuclear receptor that regulates transcription of genes involved in fatty acid oxidation and energy use. Activation of this receptor in skeletal muscle shifts metabolism toward fat burning in animal models. The compound does not burn fat directly; it changes gene expression over hours to days. Researchers study it to understand metabolic flexibility and exercise adaptation. Effects observed in rodents are not automatically expected in humans.
Preclinical research reported that GW501516 increased running endurance in mice and improved lipid profiles in some animal species. Early human trials explored effects on high-density lipoprotein cholesterol, triglycerides, and glucose handling, but the program was discontinued. Published human data are sparse and do not establish efficacy for any condition. Studies also examined PPAR delta in cancer biology, with conflicting findings across models. The relationship between receptor activation, tissue context, and disease risk remains an active area of investigation.
Anti-doping laboratories identify GW501516 and its metabolites using liquid chromatography-tandem mass spectrometry. Urine is the usual matrix, and detection can occur after the parent compound has cleared from blood. The exact detection window depends on dose, formulation, individual metabolism, and assay sensitivity. Because the compound is prohibited at all times, athletes are subject to testing in and out of competition. Analytical methods continue to improve as new metabolites and designer analogs are characterized.
Many of the opposition groups subsequently began competing for influence in the power vacuum that followed the ouster of Barre's regime. In the south, armed factions led by USC commanders General Mohamed Farah Aidid and Ali Mahdi Mohamed, in particular, clashed as each sought to exert authority over the capital. In 1991, a multi-phased international conference on Somalia was held in neighbouring Djibouti. Owing to the legitimacy bestowed on Muhammad by the Djibouti conference, he was subsequently recognised by the international community as the new President of Somalia. He was not able to exert his authority beyond parts of the capital. Power was instead vied with other faction leaders in the southern half of Somalia and with autonomous sub-national entities in the north. The Djibouti conference was followed by two abortive agreements for national reconciliation and disarmament, which were signed by 15 political stakeholders: an agreement to hold an Informal Preparatory Meeting on National Reconciliation, and the 1993 Addis Ababa Agreement made at the Conference on National Reconciliation. In 1998, the state of Puntland was established under the leadership of Abdullahi Yusuf, head of the Somali Salvation Democratic Front. In the early 1990s, due to the protracted lack of a permanent central authority, Somalia began to be characterised as a "failed state". Following the collapse of the Somali Democratic Republic in early 1991, a new phenomenon emerged – the establishment of Sharia courts to impose law and order on the volatile neighborhoods of Mogadishu.
== Advertising == In October 2008, the video game Midnight Club: Los Angeles featured Zaxbys as a restaurant on the streets of Los Angeles. California, notably, is not home to any Zaxbys locations. In 2025, Zaxbys featured actor Omar Epps as The Sauce Boss to promote the chain's signature sauces.
==== Absorption ==== 2C-B appears to have relatively low oral bioavailability. The time to peak levels is 2.0 to 2.4 hours. Peak levels of 2C-B have been reported to be 2.5 ng/mL with 10 mg orally, 3.3 to 4.6 ng/mL with 20 mg orally, and 5.4 to 6.4 ng/mL with 30 mg orally. The peak levels of 2C-B metabolites have also been described.
Once the substrate is bound and oriented to the active site, catalysis can begin. The residues of the catalytic site are typically very close to the binding site, and some residues can have dual-roles in both binding and catalysis. Catalytic residues of the site interact with the substrate to lower the activation energy of a reaction and thereby make it proceed faster. They do this by a number of different mechanisms including the approximation of the reactants, nucleophilic/electrophilic catalysis and acid/base catalysis. These mechanisms will be explained below.
Sources: en.wikipedia.org
These are shown in the figure on the right. A change from one main degradation mechanism to another appears as a knee (slope change) in the capacity vs. cycle number plot. Most studies of lithium-ion battery aging have been done at elevated (50–60 °C) temperatures for accelerated aging. Under these storage conditions, fully charged nickel-cobalt-aluminum and lithium-iron phosphate cells lose ca. 20% of their cyclable charge in 1–2 years. It is believed that the aforementioned anode aging is the most important degradation pathway in these cases. On the other hand, manganese-based cathodes show a (ca. 20–50%) faster degradation under these conditions, probably due to the additional mechanism of Mn ion dissolution. At 25 °C the degradation of lithium-ion batteries seems to follow the same pathway(s) as the degradation at 50 °C, but with half the speed. In other words, based on the limited extrapolated experimental data, lithium-ion batteries are expected to lose irreversibly around 20% of their cyclable charge in 3–5 years or 1000–2000 cycles at 25 °C. Lithium-ion batteries with titanate anodes do not suffer from SEI growth, and last longer (>5000 cycles) than graphite anodes. However, in complete cells other degradation mechanisms (i.e. the dissolution of Mn3+ and the Ni2+/Li+ place exchange, decomposition of PVDF binder and particle detachment) show up after 1000–2000 days, and the use titanate anode does not improve full cell durability in practice.
Burger King Holdings was the parent company of Burger King when it went public in 2002. Burger King derived its income from several sources, including property rental and sales through company owned restaurants; however, a substantial portion of its revenue was dependent on franchise fees. During the transitional period after 3G Capital acquired the company, Burger King's board of directors was co-chaired by John W. Chidsey, formerly CEO and chairman of the company, and Alex Behring, managing partner of 3G Capital. By April 2011, the new ownership had completed the restructuring of Burger King's corporate management and Chidsey tendered his resignation, leaving Behring as CEO and chair. Burger King Corporation is currently an independently operated subsidiary of RBI. RBI's present organizational structure includes five primary segments: Tim Hortons, Burger King, Firehouse Subs, Popeyes Louisiana Kitchen and International. International encompasses the aggregated outcomes from the operations of each brand outside the United States and Canada. Josh Kobza, the CEO of RBI, was appointed in 2023. Before taking over as CEO in February 2023, Kobza served as CFO, CTO, and COO of RBI. Tom Curtis, the president of Burger King U.S. and Canada, was appointed in 2021 and oversees the operation of the Burger King Corporation in the United States and Canada. In North America, Burger King Corporation is responsible for licensing operators and administering stores.
== Function == M-protein exhibits a different pattern of expression in cardiac and skeletal muscle, as well as fast- versus slow-skeletal muscle during development, suggesting different regulatory mechanisms for expression quantity and temporal appearance. In cardiac muscle, expression of M-protein continues to increase from neonatal to adult; however, in skeletal muscle, M-protein mRNA expression is biophasic. M-protein is initially present in both slow- and fast-skeletal muscle embryonic fibers, then M-protein is suppressed in slow fibers. The embryonic splice variant of myomesin, termed EH-myomesin, is expressed in a complementary pattern with M-protein during development in higher vertebrates. It was also shown that the mRNA expression of M-protein is exquisitely sensitive to thyroid hormone (T3); M-protein expression, but not MYOM1 or its variant, EH-myomesin, was rapidly reduced by T3 in vivo and in vitro. The M-protein promoter is responsive to T3, and was suggested to contain thyroid hormone response elements near the transcriptional start point. The giant protein titin, together with its associated proteins, interconnects the major structure of sarcomeres, the M bands and Z discs. The C-terminal end of the titin string extends into the M line, where it binds tightly to M-band constituents MYOM1 and M-protein, of apparent molecular masses of 190 kD and 165 kD, respectively.
Sources: en.wikipedia.org
It targets PPARδ, a nuclear receptor involved in lipid and energy metabolism. It does not act primarily on androgen receptors. This distinction separates it from SARMs.
Rodent studies found dose-dependent tumors in several organs. The sponsor discontinued the program over cancer concerns. Human risk from long-term use remains unknown.
Controlled human endurance trials are lacking. Animal studies show increased exercise capacity under some conditions. Anecdotal reports are not equivalent to clinical evidence.
Legal status varies by country. It is not approved as a medicine, and it is prohibited in sport. Some jurisdictions restrict import, sale, or possession.