DPP4 and obesity due to melanocortin 4 receptor deficiency: Although it has been reported that hepatocyte-secreted DPP4 in obesity encourages adipose inflammation and insulin resistance (27), and inhibition of dipeptidyl peptidase IV halts high-fat diet-induced liver cancer angiogenesis by downregulating chemokine ligand 2 (28), the DPP4 expression level in HCC tissue has been unclear.