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. 2020 Oct 19;20(1):39–63. doi: 10.1038/s41573-020-0082-8

Fig. 2. JAK1, JAK2, JAK3 and TYK2 integrate the signalling cascades of a diverse set of cytokine and growth receptors.

Fig. 2

The binding of extracellular ligands leads to pathway activation via changes to the receptors that permit trans-phosphorylation of associated Janus-associated kinases (JAKs). Activated JAKs then phosphorylate both the receptor and cognate signal transducer and activator of transcription (STAT) proteins. Activated and dimerized STATs then enter the nucleus to bind to transcriptional regulatory sites of target genes. Receptors that use JAK2 and JAK3, JAK3 alone, tyrosine kinase 2 (TYK2) alone or JAK3 and TYK2 have not been described. EPO, erythropoietin; GH, growth hormone; GM-CSF, granulocyte–macrophage colony-stimulating factor; LIF, leukaemia inhibitory factor; OSM, oncostatin M; P, phosphorus; TPO, thrombopoietin; TSLP, thymic stromal lymphopoietin.