ERBB3 and obesity due to melanocortin 4 receptor deficiency: reported that BAT controls liver lipogenesis through the secretion of the growth factor Nrg4.[7] BAT‐secreted Nrg4 acts on ErbB3/ErbB4 signaling in hepatocytes, attenuates hepatic lipogenic signaling, and preserves glucose and lipid homeostasis in obesity.