RAD51 and cancer: However, several cancers, including prostate, colorectal, pancreatic, breast, and non-small-cell lung cancers, have demonstrated an overexpression or activation of various DNA repair proteins, such as BRCA1/2, RAD51, ATM, MRE11, excision-repair cross-complementation (ERCC), and DNA repair protein complementing XP-C cells (XPC), which reduce the sensitivity of the tumors to chemotherapy and radiotherapy [20,21,22,23,24].