In Vitro: Atg4B-IN-2 (compound 21f) (1-10 μM; 2 hours) restores the p62 expression in cells treated with AF (amino acid-free) in a dose-dependent manner. Atg4B-IN-2 (1 and 5 μM; 2 hours) decreases moderately autophagic vesicles at 1 μM, and almost completely inhibits autophagy at 5 μM. Atg4B-IN-2 (5 μM; 2 hours) inhibits Abi-induced autophagy and significantly augments apoptotic cell death and sensitivity to Abi.