TYK2 belongs to the family of non-receptor janus tyrosine kinases, which regulate a spectrum of cellular functions occurring downstream of activated cytokine receptors in the lympho-hematopoietic system. Immunological stimuli, such as interferons and cytokines, recruit STAT transcription factors to the cytokine receptor where TYK2 is associated. TYK2 then phosphorylates proximal STAT factors, which subsequently dimerize, translocate to the nucleus, and bind to cis elements upstream of target gene promoters to regulating transcription. The canonical JAK-STAT pathway is integral to maintaining a normal immune system by stimulating proliferation, differentiation, survival, and host resistance to pathogens. Cytokine induced pro-inflammatory responses are attractive targets for anti-inflammatory therapies, specifically at the level of Jak-STAT signaling.