PCNA and cancer: In addition, as one of the hallmarks of cancers, DNA repair deficiency is an important cause of genomic instability.33 Bielinsky et al. revealed that FEN1 drove DNA hypersensitivity in a PCNA-dependent manner.34 A mouse model carrying an FEN1 mutation that eliminated the FEN1-PCNA interaction was reported in a study, and the DNA breaks caused by this mutation promoted the development of aneuploid cancers.14 Given the critical role that FEN1 plays in DNA damage repair, we conducted DNA damage-related experiments after downregulating FEN1.