PTEN and neoplasm: Additionally, PTEN conditional knockout leads to tumor growth in multiple organs, such as the mammary gland, skin, and prostate [27, 28].Thus, PI3K/PTEN/Akt/mTOR pathway activation may initiate tumorigenesis through the following mechanisms: (i) inhibition of apoptosis; (ii) autophagy; (iii) promotion of metastasis; or (iv) resistance to chemotherapy.