JAK1 is required in the JAK/signal transducer and activator of transcription (STAT) pathway for the activation of STAT1 and STAT2 in response to interferon [13] Previous studies have reported that the JAK/STAT pathway had a central role in driving normal and cancer stem cell growth, and deregulation of the pathway was implicated in the promotion of oncogenic phenotypes, including tumorigenesis, proliferation, anti-apoptosis, invasion, angiogenesis, metastasis, and immune evasion [14–16]. The gene discussed is STAT1; the disease is cancer.