Signal Transducers and Activators of Transcriptions (STATs) are a family of cytoplasmic latent transcription factors that are activated to regulate gene expression in response to a large number of extracellular signaling polypeptides including cytokines, interferons, and growth factors. STAT5, which consists of two isoforms STAT5α and STAT5β, is known to be overactive in several kinds of leukemias and various solid tumors. STAT5 Inhibitor is a cell-permeable, nonpetidic nicotinoyl hydrazone that suppresses STAT5 by targeting its SH2 domain (IC50 = 47 μM against STAT5β SH2 domain EPO peptide binding activity). Comparatively, this compound exhibits reduced potency towards inhibiting the SH2 domain of STAT1, STAT3, or Lck (IC50 > 500 μM). STAT5 Inhibitor has been shown to block STAT5/STAT5 DNA binding in K562 nuclear extracts.
