TP53 and cancer: For instance, miRNA-34 family members are regulated by p53 in DDR and have roles in cell-cycle checkpoint and apoptosis.26, 27, 28, 29 Many miRNAs (miR-24, miR-16, miR-421 and miR-138) have roles in DNA damage and repair.30, 31, 32, 33 MiRNA-regulated DDR may have the potential to improve the efficacy of cancer therapy relying on induction of DNA damage.