BECN1 and breast cancer: Autophagy is robustly activated in cancer cells under a multitude of stress conditions, including starvation, growth factor deprivation, hypoxia, damaging stimuli and proteasome inhibition, so elevated levels of autophagy have been observed in many tumor types, e.g. the essential autophagy gene Beclin1 was upregulated in colorectal cancer, gastric cancer, liver cancer, breast cancer, and cervical cancer [228–231], suggesting that the enhancement of autophagy can promote tumorigenesis and overexpression of the Beclin1 plays a crucial role in tumor formation.