Autophagy is a multi-step process that involves the degradation and digestion of intracellular components by the lysosome. This process allows cells to efficiently mobilize and recycle cellular constituents, and also prevents the accumulation of damaged organelles, misfolded proteins, and invading microorganisms. mTOR, whose activation is controlled by phosphoinositide 3-kinase (PI3K), is a key regulator of autophagy. 3-Methyladenine (3-MA) is a specific inhibitor of PI3K activity and one of the most widely used inhibitors of the initial phase of the autophagic process: the sequestering of cytoplasmic material by the lysosome. At 5 mM, 3-MA inhibits protein degradation in rat hepatocytes by 65%. 3-MA has been shown to block class I, class II, and class III PI3Ks, including some downstream targets, and to suppress the invasion of highly metastatic human fibrosarcoma HT1080 cells at 10 mM.
