May act as a papain-like cysteine protease inhibitor to modulate the host immune response against tumor cells. Also functions as an inhibitor of UV-induced apoptosis via suppression of the activity of c-Jun NH(2)-terminal kinase (JNK1).
Subcellular locations: Cytoplasm
Seems to also be secreted in plasma by cancerous cells but at a low level.
Squamous cells. Expressed in some hepatocellular carcinoma (at protein level).