Because mature adipocytes are not formed in the intercellular matrix of the skeletal muscle of obesity-resistant mice, but adipose precursor somatic cells that have not differentiated into mature adipocytes, such as fibroblasts (Figure 3E), the perilipin on the surface of lipid droplets in these adipose precursor somatic cells is mainly PLIN2. The gene discussed is PLIN2; the disease is obesity due to melanocortin 4 receptor deficiency.