MYC and obesity due to melanocortin 4 receptor deficiency: In intestine-specific FXR knockout mice, the expression of ceramide synthesis genes SMPD3/4, SPTLC2 and CERS4 were suppressed in the intestine, and ceramide synthesis levels were reduced, which contributed to the improvement of HFD-induced obesity, insulin resistance and hepatic steatosis 143, MYC has an important role as a proto-oncogene in cell proliferation, apoptosis and metabolic processes.