JAK1 is a human tyrosine kinase protein essential for signaling certain type I and type II cytokines. It interacts with the common gamma chain (γc) of type I cytokine receptors to elicit signals from the IL-2 receptor family (e.g. IL-2R, IL-7R, IL-9R, and IL-15R), the IL-4 receptor family (e.g. IL-4R and IL-13R), the gp130 receptor family (e.g. IL-6R, IL11R, LIF-R, OSM-R, corticotrophin-1 receptor (CT-1R), ciliary neurotrophic factor receptor (CNTF-R), neurotrophin-1 receptor (NNT-1R) and Leptin-R). It is also important for transducing a signal by type I (IFN-α/β) and type II (IFN-γ) interferons and members of the IL-10 family via type II cytokine receptors. Jak1 is critical in initiating responses to multiple major cytokine receptor families. Loss of Jak1 is lethal in neonatal mice, possibly due to difficulties suckling. Expression of JAK1 in cancer cells enables individual cells to contract, potentially allowing them to escape their
tumor and metastasize to other parts of the body.
Ba/F3 cell, a murine interleukin-3 dependent pro-B cell line, is a popular system for exploring both kinases and their inhibitors, because some protein kinases can render the Ba/F3 cells to be depended on the activation of the kinases instead of IL-3 supplement, while their inhibitors can antagonize the kinase-dependent growth effects.
