A microarray study characterizing Olaparib sensitivity in breast cancer cell lines have identified six DNA repair genes that were significantly down-regulated (MRE11A, NBS1, TNKS, TNKS2, XPA, XRCC5) and two that were significantly up-regulated (CHEK2, MK2) in sensitive cell lines relative to resistant cell lines [26]. This evidence concerns the gene CHEK2 and breast cancer.