Protein tyrosine kinase (PTK) inhibitors are potential antiproliferative agents for diseases caused by the hyperactivity of protein tyrosine kinases. Tyrphostins are a class of antiproliferative compounds which act as protein tryrosine kinase blockers. PTK inhibitors which preferentially inhibit the epidermal growth factor (EGF) receptor kinase block EGF-dependent cell proliferation.{14963} AG-17 is an inhibitor of epidermal growth factor (EGF) receptor kinase with an IC50 value of 460 µM in the human epidermoid carcinoma cell line A431.{14963}