TNFSF10 and obesity due to melanocortin 4 receptor deficiency: Since both the cellular source of serum TRAIL and the mechanisms of secretion of soluble TRAIL are not fully understood, it is unclear whether the direct correlation of TRAIL concentration with obesity reflects an enhanced synthesis and/or release from adipocytes or the consequence of other biological pathways activated by adipose tissue and/or increased levels of circulating lipoproteins.