Western blotting showed that the expression of cycle-related proteins CyclinD1, and PCNA increased (P < 0.05) (Fig. 6f, g), indicating that knockdown of HERPUD1 induces ovarian cancer cells to enter S phase from G0/G1 by upregulating the expression of these proteins and causing S phase block, which affects cell cycle progression. Here, PCNA is linked to ovarian cancer.