PCNA and nasopharyngeal carcinoma: Inhibits the proliferation of NPC cell lines;colony formation was promoted in normal preosteoblast MC3T3-E1 cells and was markedly inhibitedin NPC tumour cells;increases G1 phase, reduces S phase in NPC cell lines;markedly inhibits migration in CNE-2, Sune-1 and CNE-1 cells;promotes NQO1 protein expression in NPC cell lines;significantly decreases the expression of PCNA and MMP9 in NPC cells.