As poorly differentiated RB is associated with multiple high‐risk histopathologic factors to some extent (Kashyap et al., 2012), the negative role of UHRF1 in photoreceptor differentiation may present a novel insight into the tumor‐promoting functions of UHRF1 in RB cells in addition to its implication in ROS homeostasis and protective roles against HDAC inhibitor‐induced cell death (Fig. 8). The gene discussed is UHRF1; the disease is retinoblastoma.