ANGPTL4 and obesity due to melanocortin 4 receptor deficiency: Recently, it has been found that ANGPTL4 is upregulated in human adipocytes in response to hypoxia15–17, and studies using microarray-based technology have reported that the expression of ANGPTL4 is significantly upregulated in obesity, in early18 and late phases of adipocyte differentiation19, as well as in fat samples from obese subjects20,21.