We have further shown that KCO mice have comparable tumor latency and survival with mice harboring an additional driver Trp53 mutation (e.g., Pdx1-Cre;KrasLoxP-STOP-LoxP-G12D;Trp53+/LoxP-STOP-LoxP–R172H [KPC]) (Muzumdar et al, 2016; Chung et al, 2020), arguing that obesity can effectively substitute for a second genetic hit in tumor progression. This evidence concerns the gene MAP6 and obesity due to melanocortin 4 receptor deficiency.