S-Ruxolitinib is the chirality of INCB018424, is a potent and selective small-molecule Janus kinase 1 (JAK1) and JAK2 inhibitor. It was initially developed to target the constitutive activation of the JAK-STAT pathway. Janus kinases (JAKs) are a family of cytoplasmic tyrosine kinases that mediates signals from the receptors for various cytokines and growth factors that have a key role in haematopoiesis and immune function. Ruxolitinib maintains its anti-JAK activity by competitive inhibition of the ATP-binding catalytic site of the kinase domain. Ruxolitinib is well absorbed at >95%. Exposure of JAK2V617F-positive Ba/F3 cells to ruxolitinib iss shown to result in reduced cellular proliferation.
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