PTEN and cancer: In addition, X-linked apoptotic inhibitors and E3 ubiquitin ligase WW domain (WWP2) is also thought to interacts with and ubiquitinate PTEN, which regulates PTEN degradation via ubiquitination pathway.411,412 It is reported that WWP2 mediates cellular apoptosis, which is a necessary condition for tumorigenesis.413 Therefore, WWP2 might play a crucial role in the survival of cancer cells in a PTEN dependent way.414 Both gene ablation and drug inhibition of WWP1 can activate PTEN and release tumor suppressive activity.