NFKB1 and breast cancer: Interestingly, similar to inhibiting NF-κB [88], RAP1 inactivation by siRNAs sensitizes breast cancer cell lines to apoptosis induced by TNFα (MCF7, BT474, MDA-MB-231) and adriamycin (BT474, MDA-MB-231), and this correlated with the loss of p65 phosphorylation at Ser536 in these cells.