JAK3, janus kinase 3, is a non-receptor protein tyrosine kinase involved in the interferon-alpha/beta/gamma pathway and is a member of the JAK/STAT signaling pathway (PMID: 15575979). Simple variants in JAK3 are seen in about 1% of all tumors including about 4% of skin and small intestine tumors, and 2% of CRC. JAK3 inhibitors are under development and have shown activity in preclinical trials (PMID: 25146434)