USP34 and obesity due to melanocortin 4 receptor deficiency: For example, Christodoulides et al. reported that mutation C256Y in WNT10B was associated with overweight or obesity because the mutation was unable to activate canonical Wnt pathway [26]; and Choi et al. found that indirubin-3′-oxime (I3O), also an activator of the Wnt signaling like USP34, inhibited the development of obesity in high-fat diet fed mice [27].