Consistent with previous work in prostate cancer cells (22), we found that ectopic expression of V5-ESRRG-WT in HEK293 cells induced p21 expression associated with hypophosphorylation (activation) of RB1, whereas knockdown of endogenous ESRRG resulted in depletion of p21 and hyperphosphorylation (inactivation) of RB1 (Fig. 4F). Here, ESRRG is linked to prostate cancer.