In both retinoblastoma cell lines, the levels of Bcl-2, CDK1 and PCNA were significantly upregulated in the PAX6 inhibition study groups than in negative GFP-control groups (Bcl-2, t=−5.90, P<0.05 and t=−4.86, P<0.05, resp. Here, PCNA is linked to retinoblastoma.