RRM2 and cervical squamous intraepithelial neoplasia: On top of this, genes involved in mismatch repair pathway (EXO1, MSH2, PCNA, POLE2, RFC3/4/5), homologous recombination pathway (BRCA1, RAD51AP1), DNA damage signaling (CHEK1, RRM2, CCNB1/2, CDK1), and Fanconi anemia pathway (FANCI, UBE2T) were also over-expressed in high CIN samples.