Nonetheless, because treatment with a pan-sirtuin inhibitor (nicotinamide) and a SIRT1-specific inhibitor (EX-527) delayed cyst growth in Pkd1 knock-out mouse embryonic kidneys, Pkd1 conditional knock-out postnatal mice, and Pkd1 hypomorphic mice, it is unclear whether sirtuin 1 is an interesting drug target in combined obesity and ADPKD (Zhou et al., 2013). Here, PKD1 is linked to obesity due to melanocortin 4 receptor deficiency.