This gene encodes a non-receptor tyrosine kinase involved in cytokine and growth factor signaling. The primary isoform contains a FERM domain for receptor association, an SH2 domain for STAT binding, a pseudokinase domain, and a C-terminal kinase domain. Cytokine binding activates the kinase, which then phosphorylates and activates STAT proteins. Growth factors like TGF-beta 1 also activate this kinase, influencing gene transcription. Mutations in this gene are linked to inflammatory diseases and cancers. It is a target of IL6, involved in immune response and inflammation. Disruption of the IL6/JAK2/STAT3 pathway leads to increased cellular proliferation and myeloproliferative neoplasms. A mutation in the pseudokinase domain causes constitutive activation, leading to hypersensitivity to cytokines. This gene and its pathway are therapeutic targets for inflammatory conditions. Alternative splicing produces multiple isoforms.