This combined effect, perhaps, contributes to increase aggressiveness and drug resistance phenotypes in no/low BRCA1/p220 expressing breast tumors, and support the view that the two proteins affect a linear pathway(s), in which BRCA1/p220 silencing and/or BRCA1-IRIS overexpression gives survival advantages to cancer cells and promotes the formation of death resistant TN/BL breast cancer cells. This evidence concerns the gene BRCA1 and breast cancer.