PCNA and non-small cell lung carcinoma: A recent preclinical study showed that in H1975 tumors transplanted mice model, the expression of Ki-67 and proliferating cell nuclear antigen (PCNA) were significantly decreased after the intervention of apatinib plus gefitinib compared with gefitinib or apatinib alone, indicating that the addition of apatinib may synergistically inhibit NSCLC growth and improve the efficacy of gefitinib.