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receptors triggers activation of the transcription factor NF-κB (see
VetBooks.ir Fig. 8.4).
Another large receptor family, the group I cytokine receptor
family, includes among its members the receptors for IL-2 (β chain),
IL-4, IL-5, IL-6, IL-12, granulocyte colony-stimulating factor (G-
CSF), and granulocyte-macrophage colony-stimulating factor (GM-
CSF) (Fig. 8.8). It also includes the common γ chain of IL-2, IL-4, IL-
7, IL-9, and IL-15 receptors. These receptor chains dimerize in the
presence of the ligand and form complexes with a group of kinases
called Janus kinases (JAKs). JAKs in turn phosphorylate a cytosolic
protein called STAT (signal transducers and activators of
transcription). The STAT then dimerizes to form an active
transcription factor. Depending on the specific JAKs and STATs
used, these may enhance or suppress cytokine signaling.
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