Signal Transducers and Activators of Transcription (STATs) are a family of transcription factors that play roles in transmitting signals from the cell surface to the nucleus in response to cytokines, growth factors, and some hormones. STATs are involved in a wide range of cellular processes, including immune responses, differentiation, and apoptosis. STAT activation begins when cytokines or growth factors, such as IFNs, IL-6, or GH, bind to their respective cell surface receptors. Ligand binding induces conformational changes in the receptor, activating receptor-associated Janus kinases (JAKs). JAKs phosphorylate tyrosine residues in the receptor's cytoplasmic domain, creating docking sites for STATs. Once recruited, STATs become phosphorylated on a critical tyrosine residue (usually located in the SH2 domain) by JAKs. Phosphorylation of STATs promotes their dimerization, with most STATs forming homodimers, although some (e.g., STAT1 and STAT2) can also form heterodimers. Dimerized, phosphorylated STAT dimers translocate to the nucleus, binding to STAT-binding elements (SBEs) and regulate the expression of target genes by recruiting cofactors and RNA polymerase II to promote gene transcription. STAT activation is negatively regulated to prevent prolonged signalling via regulators such as suppressors of cytokine signaling (SOCS) proteins which inhibit JAK activity thereby promoting STAT dephosphorylation and inhibition. STAT1 and STAT2 are STATs primarily involved in the response to interferons (IFNs), such as interferon-alpha (IFN-α) and interferon-beta (IFN-β). They therefore play a central role in antiviral immunity but are also involved in regulating cell growth and apoptosis. STAT3 is activated by other cytokines and growth factors, including interleukin-6 (IL-6) and epidermal growth factor (EGF). STAT3 plays important roles in inflammation, tissue regeneration, and cell survival. Dysregulation of STAT3 is associated with cancer and chronic inflammatory diseases. Abnormal phosphorylation of STAT3 is a common feature in many cancer types. Phosphorylation is a key regulatory step in the activation of STAT3 and activated signaling pathways in cancer cells, such as those involving growth factor receptors (e.g., EGFR, PDGFR) can lead to excessive phosphorylation of STAT3, rendering it constitutively active. STAT4 is predominantly activated by interleukin-12 (IL-12) and interleukin-23 (IL-23). It is a key regulator of T-helper 1 (Th1) cell differentiation and the immune response against intracellular pathogens. Finally, STAT5a and STAT5b are activated by several cytokines, including growth hormone (GH) and erythropoietin (EPO). They are essential for cell growth, differentiation, and haematopoiesis. STAT proteins play important roles in various immune responses. For example, STAT1 and STAT2 are essential for the antiviral response mediated by type I IFNs. STAT4 regulates Th1 T-cell differentiation, which is crucial for the immune response against intracellular pathogens. STAT3 activation is a key driver of inflammation, influencing the expression of pro-inflammatory genes. Dysregulated STAT3 signalling can also lead to chronic inflammatory conditions, whilst STAT signaling is essential for cell growth, differentiation, and survival. For example, STAT5 is critical for haematopoiesis and promotes the survival and proliferation of hematopoietic stem and progenitor cells by regulating the expression of genes involved in cell cycle progression, anti-apoptotic pathways, and cell growth. We offer a comprehensive product range of research reagents for investigating STATs, including STAT3 antibodies, JAK2 antibodies, STAT1 antibodies, STAT3 ELISA Kits, and STAT6 ELISA Kits. Explore our full STATs product range below and discover more, for less.