SIRT1 and obesity due to melanocortin 4 receptor deficiency: In both male and female rats, the obesity group of animals showed an upregulation of the oncogenes SURVIVIN/BIRC5 and MYC, together with a downregulation of genes linked to antioxidant protection, GSTM2, SIRT1 and SIRT6, and the tumor suppressors TGFB1, TP53 and PTEN (Figure 1A,B).