Tyrphostin A25 is a cell-permeable, competitive and reversible inhibitor of substrate binding on protein tyrosine kinases. In cultured rat hepatocytes, Tyrphostin A25 has been shown to inhibit endocytosis of tyramine-cellobiose-asialoorosomucoid (TC-AOM). It has also shown to inhibit neuromedin B-induced phosphorylation of focal adhesion kinase (p125FAK). Inhibits EGFR (epidermal growth factor receptor) tyrosine kinase (IC50=3 M ) and the GTPase activity of transducin. In small cell lung cancer cells tyrphostin A25 has been observed to obstruct neuropeptide and basal stimulated growth. In addition it has blocked the induction of inducible NO synthase in glial cells and in human leukemic cell lines has induced apoptosis.
