REV-ERBα is a nuclear receptor and transcription repressor that coordinates circadian rhythm and metabolic pathways in a heme-dependent manner.[1],[2] SR8278 is an antagonist of REV-ERBα (EC50 = 0.47 µM), blocking activation of the receptor by the synthetic agonist GSK 4112.[2] Moreover, SR8278 stimulates the expression of two REV-ERBα target genes involved in the regulation of glucose production, glucose 6-phosphatase and phosphoenolpyruvate carboxykinase, in liver cells.2 SR8278 has been used, with GSK 4112, to elucidate the role of REV-ERBα in regulating glucagon secretion in pancreatic alpha cells.[3]