TP53 and obesity due to melanocortin 4 receptor deficiency: Given that p53 plays an important role in the regulation of lipid metabolism, it may not be surprising that p53 has been demonstrated to be involved in systemic conditions related to lipid metabolism, such type 2 diabetes and obesity (Yahagi et al., 2003; Minamino et al., 2009; Wang et al., 2013).