This gene encodes a member of the peptidase C1 (papain) family of cysteine proteases. Alternative splicing results in multiple transcript variants, which encode preproproteins that are proteolytically processed to generate mature protein products. This enzyme is secreted by antigen-presenting cells during inflammation and may induce pain and itch via activation of G-protein coupled receptors. Homozygous knockout mice for this gene exhibit impaired wound healing, reduced tumorigenesis in a pancreatic cancer model, and reduced pathogenesis in a myasthenia gravis model. [provided by RefSeq, Aug 2015]