BRCA1 and breast cancer: Although AKT activation promotes BRCA1 expression through phosphorylation [65], it has been shown that BRCA1 can downregulate AKT activation in different ways: by acting on upstream kinases of AKT [31,66], by ubiquitin-mediated proteasomal degradation or by activating a protein serine/threonine phosphatase PP2A in breast cancer cells (Figure 1) [67].