Insulin may promote breast cancer via direct mitogenic effects of insulin, but also through reducing levels of sex hormone binding globulin, and associated increase in bioavailable oestrodiol and testosterone, and increased bioavailable insulin like growth factor which stimulate downstream Ras/MAPK and phosphoinositide 3-kinase/protein kinase B [PI3K/Akt] signaling pathways. Here, AKT1 is linked to breast cancer.