PTEN and breast cancer: PI3K pathway play a crucial role in development and progression of cancers mostly breast cancer (Boyault et al., 2012), in this study we focused on the main regulators of the PI3K pathway (PIK3CA which acts as PI3K activator and PTEN acts as PI3K inhibitor and tumor suppressor), and were examined to test whether an increased PIK3CA expression and decreased PTEN expression in breast carcinoma and normal breast tissue.