The genes that interacted with 24 known genes to form a protein interaction network were ABCC1, ABCC3, ABCC5, ABCC6, ABCG2, APEX2, ARAF, ATM, FEN1, GBA, HMGB1, LIG1, LIG3, MCM3AP, MDK, OGG1, PCNA, POLB, SMUG1, TDG, UNG, and XRCC1 (Fig. 4), indicating that these genes might be functionally related and suggesting that the selected genes might also be related to CIN. The gene discussed is PCNA; the disease is cervical squamous intraepithelial neoplasia.