Remarkably, combination of PI3K pathway inhibitors with chemotherapeutic drugs such as doxorubicin, cisplatin, or topotecan results in enhancing cancer cell killing properties in BRCA1-defective breast cancer cells (69, 70), suggesting that the PI3K/AKT pathway may be activated in BRCA1-defective breast cancer cells. Here, AKT1 is linked to breast cancer.