Janus kinase (JAK) is an intracellular non-receptor tyrosine kinase. There are four members of the JAK family: JAK1, JAK2, JAK3, and Tyrosine kinase 2 (TYK2). JAK can link cytokine signals from membrane receptors to activators of transcription (STAT), transducing cytokine-mediated signals via the JAK-STAT signaling pathway. When the receptor...