Moreover, the identification of posttranslational modification that modulate EZH2 enzymatic activity e.g., Ser 21 phosphorylation and non-histone targets of EZH2 such as proliferating cell nuclear antigen (PCNA) may open new avenues to understand the molecular functions of EZH2 and the impact of EZH2 inhibitors in cancer therapy. Here, PCNA is linked to cancer.