PTEN and cancer: For example, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor that counters phosphatidylinositol 3 -kinase (P13K) activation.18 P13K stimulates AKT in a survival signal; thus, PTEN silencing allows P13K AKT activation and inappropriate survival of cancer cells.18 Loss of PTEN allows unchecked cell cycle progression.