It has been reported that ATRA can enhance the efficacy of the anti‐PD‐1 antibody pembrolizumab in stage IV melanoma patients,[19] and PD‐L1 has been reported as a substrate of β‐TrCP.[20] In addition, in Otud6b WT mice, we found that ATRA treatment significantly reduced the expression levels of PD‐L1, but not in Otud6b cKO mice (Figure 7G). This evidence concerns the gene BTRC and melanoma.