In vitro activity: STAT5-IN-1 (also known asSTAT5 Inhibitor) is a STAT5 ( signal transducer and activator of transcription 5) inhibitor with IC50 of 47 μM for STAT5β isoform. STAT5-IN-1 is a cell permeable non-petide nicotinoyl hydrazone which suppresses STAT5 via binding to the SH2 domain. STAT5 is a member of the STAT family of proteins that is implicated in cell growth and differentiation. STAT5 functions in various biological processes such as homeostasis of hematopoietic stem cells, development of blood cells, growth hormone effects, and differentiation of mammary epithelium. STAT5 has been reported as a therapeutic target for the treatment of human cancers.

Kinase Assay: The signal transducer and activator of transcription 5 (STAT5) is a member of the STAT family of proteins, implicated in cell growth and differentiation. STAT5-IN-1 inhibits STAT5 by binding to the SH2 domain. The functions of the SH2 domains of STAT3, STAT1, and of the tyrosine kinase Lck are inhibited to a lesser degree (IC50>500 μM). STAT5-IN-1 block STAT5/STAT5 DNA binding in K562 nuclear extracts. Substitution of the hydrogen at C6 of the chromone ring by an ethyl group does not affect activity of STAT5-IN-1 against STAT5β, but leads to complete loss of selectivity against other STAT family members.

Cell Assay: