JAK1 is a human
tyrosine kinase protein essential for signaling for 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,
IL-11R,
LIF-R,
OSM-R,
cardiotrophin-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 plays a critical role 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.