3-Methyladenine inhibits autophagy by blocking autophagosome formation via inhibition of type III phosphatidylinositol 3-kinases (PI-3K). It protects 1321N1 astrocytoma cells against pyocyanin and hydroxyphenazine-induced toxicity. Inhibition of autophagy by 3-MA leads to enhanced apoptosis induced by a variety of agents including celastrol, cisplatin and sorafenib in several different cell lines.