In order to verify the causal relationship of DNMT1 on CDKN2B methylation during diabetic retinopathy, siDNMT1 and siDNMT1+siCDKN2B were transfected into RGCs, and MTS and flow cytometry were used to test their effects on cell proliferation. This evidence concerns the gene CDKN2B and diabetic retinopathy.