Aberrant Akt expression and hyperactivation of Akt, which was commonly occurred in human cancers via mechanisms including loss of PTEN, mutation or amplification of phosphatidylinositol 3-kinase (PI3K), activation or mutation of receptor kinases, and oncogenes that affect upstream modulators of Akt, therefore, promote cancer cell survival and proliferation. The gene discussed is PTEN; the disease is cancer.