Tyrphostin A23 belongs to a novel class of low molecular weight proteins that inhibit protein tyrosine kinase and block the EGF-dependent autophosphorylation of the receptor. It has been considered as potential anti-cancer drug. It inhibits pancreatic cancer cell growth in vitro. Inhibition of EGF receptor by tyrphostin A23 was associated with a significantly increased proportion of apoptotic cells in human prostate cancer DU145 cell culture.