MERTK and obesity due to melanocortin 4 receptor deficiency: mRNA expression alterations in the wild-type ATMs reflect the change in the composition of MΦs in obesity: in non-obese mice, the ATMs are tissue-resident MΦs known to express high levels of Mer but low levels of pro-inflammatory cytokines, while in HFD mice, pro-inflammatory MΦs infiltrate the adipose tissue and express low levels of Mer [26].