Mutational landscape of regulators of the PI3K/AKT pathway in breast cancer. A. Copy-number and mutational data on ERBB2, PIK3CA, AKT 1–3 and phosphatases PTEN and INPP4B in breast cancer (TCGA, 2015). B. Mutation rates of the genes encoding these components in ERBB2-amplified breast cancer show that, after PI3K coding-gene, the gene encoding AKT3 is the most frequently altered, mainly by means of copy number gain.