AKT1 and breast cancer: The serine/threonine kinase AKT, a major downstream mediator of the phosphoinositide 3-kinase (PI3K)-pathway, was shown to regulate cancer progression and determine the metastatic potential of breast cancer cells by promoting migration and invasion, e.g. by upregulation of integrin β1 and matrix metalloproteinase (MMP) expression [8,9].