Fig. 1. Starvation and growth-factor deprivation stimulates cell signaling cascades (the key intermediates identified above) that ultimately result in the initiation of autophagy. The autophagosome matures and is trafficked to lysosomes where it fuses and creates the autolysosome. The autolysosome digests cellular biomass and eliminates toxins, facilitating a host of favorable nutrient and growth conditions. AMPK, AMP-activated protein kinase; mTOR, mechanistic target of rapamycin. Adapted from Farrow JM, et al. Nat Rev Urol 2014;11:508-16, with permission from author C.P.E. [13].