CDK13 and posterior cortical atrophy: Correspondingly, colony formation assay also revealed that CDK13 overexpression-enhanced colony formation was significantly attenuated by interfering with interactions between E2F5 and CDK13 through depleting Pol ll with siPol II in PC3 and 22RV1 cells (Fig. 3h), further supporting that Pol ll mediated-interaction of CDK13 with E2F5 facilitates the PCa cell proliferation.