Cysteine Protease ATG4C (ATG4C) belongs to the peptidase C54 family. It is required for autophagy, which cleaves the C-terminal part of either MAP1LC3, GABARAPL2 or GABARAP, allowing the liberation of form I. A subpopulation of form I is subsequently converted to a smaller form which is considered to be the phosphatidylethanolamine (PE)-conjugated form, and has the capacity for the binding to autophagosomes. ATG4C is a cytoplasmic protein and high expressed in skeletal muscle, liver, testis and heart. ATG4C can be inhibited by N-ethylmaleimide.