Thus, we demonstrated that: (1) the effect of an IGF1R blocking antibody on inhibition of IGF1-mediated proliferation is reduced in breast cancer cells expressing a mutant BRCA1 compared to cells expressing a wild-type BRCA1; and (2) the synergistic effect of anti-IGF1R therapy along with chemotherapy is similarly reduced in cells containing a mutant BRCA1 gene [89]. This evidence concerns the gene BRCA1 and breast cancer.