Therefore, AKT integrates various upstream inputs and triggers downstream network activities [17].While PTEN mutations are relatively uncommon in breast cancer (< 5%), PTEN protein loss is frequent (~ 30%) [12, 22].This loss is reported to be caused by various mechanisms, such as promoter methylation, loss of heterozygosity, and regulation at the RNA or protein level. The gene discussed is PTEN; the disease is breast cancer.