Cells that lack Rad51C, a Rad51 paralog, are reported to be highly sensitive to olaparib [32], and two murine breast cancer models have revealed that a pan-Class I PI3K inhibitor, BKM120, has the ability to inhibit Rad51, which was shown to lead to an increase in the anti-tumor effect of olaparib [33, 34]. Here, RAD51 is linked to breast cancer.