Defective regulation of autophagy in cancers suggests that autophagy is a true tumor-suppressor pathway[41,42] and this is further supported by the fact that several commonly activated oncogenes (for example, those encoding PI3K, TOR, Bcl-2) inhibit autophagy, whereas commonly mutated or epigenetically silenced tumor suppressor genes (such as those encoding p53, PTEN, TSC1/TSC2) stimulate autophagy[43]. Here, PTEN is linked to cancer.