ACVR1C and obesity due to melanocortin 4 receptor deficiency: In conclusion, human adipose tissue expresses receptors required for paracrine or autocrine effects of activin B. The effects of obesity on adipose tissue expression of ALK7 and INHBB genes, the strong correlations with markers of the metabolic syndrome and the dysregulation between ligand and receptor transcripts in subjects with glucose intolerance indicate that the adipokine activin B has hitherto unrecognized metabolic effects.