Tyrphostins are tyrosine phosphorylation inhibitors that act by inhibiting tyrosine kinases. AG957 is a tyrphostin that targets transforming Bcr-Abl fusion proteins (p185Bcr-Abl, p210Bcr-Abl), as well as normal c-Abl (IC50s = 4.3, 1, and 7.1 μM, respectively, for human proteins). It also inhibits epidermal growth factor receptor (IC50 = 0.25 μM). As the constitutively-active 210 kDa Bcr-Abl fusion protein commonly occurs in chronic myelogenous leukemia (CML) cells, AG957 is commonly used to study Bcr-Abl signaling in the CML K562 cell line. AG957 is also used to study signaling through c-Abl.
