Janus kinase–signal transducer and activator of transcription pathway (JAK-STAT pathway)

The **Janus kinase–signal transducer and activator of transcription pathway** is a critical intracellular signal transduction cascade that mediates the effects of numerous cytokines, growth factors, and hormones. Upon ligand binding to specific cell-surface receptors, receptor-associated Janus kinases (JAKs) are activated through phosphorylation. These activated kinases then phosphorylate the receptors themselves, creating docking sites for signal transducers and activators of transcription proteins (STATs). Once recruited, STATs are phosphorylated by JAKs, dimerize, and subsequently move into the nucleus where they regulate gene expression. This tightly regulated process controls essential biological functions such as immune responses, cell growth/proliferation, differentiation, apoptosis, hematopoiesis, inflammation control—and its dysregulation is implicated in a wide range of diseases including cancers (notably myeloproliferative neoplasms), autoimmune disorders like rheumatoid arthritis or psoriasis, infectious diseases such as COVID‑19 hyperinflammation syndromes,[1][2][3][5] among others. The development and clinical use of small-molecule inhibitors targeting various components—primarily the JAK family—have established this signaling axis as an important therapeutic target across multiple indications. **Note:** The entry "Janus kinase–signal transducer and activator of transcription pathway" refers to a **signaling pathway**, not a single molecule or protein target; thus it is not itself a canonical druggable entity but rather encompasses multiple molecular targets within it—including individual Janus kinases (*e.g.*, JAK1/JAK2/TYK2) or specific STAT proteins (*e.g.*, STAT3)—each with their own distinct properties.[1][3] For structured data purposes focused on drug targets at the molecular level rather than pathways as wholes ("receptor", "enzyme", etc.), consider mapping queries more specifically to individual members such as "Janus kinase 1" or "Signal transducer and activator of transcription 3".

Other names

JAK/STAT pathwayJanus kinase–STAT pathwayJAK-STAT signaling cascade

Inhibition of Janus kinases to block downstream STAT activation and gene transcription; Modulation of cytokine signaling to reduce inflammation or abnormal cell proliferation