PCNA and cervical cancer: Our study results indicated that metformin combined with everolimus therapy could significantly inhibit cell growth (as shown by reduced cell viability and PCNA protein level) and promote cell apoptosis (as evidenced by upregulation of Bax, cleaved-PARP-1, and cleaved caspase-3 protein levels) in both human cervical cancer cell lines (Figure 1, Figure 2 and Figure 5); this combined treatment also inhibited xenograft animal tumor growth to produce markedly synergistic anticancer effects in a mouse model (Figure 8).