Notes: Protein tyrosine kinase (PTK) inhibitors are potential antiproliferative agents for diseases caused by the hyperactivity of PTKs. Tyrphostins are a class of antiproliferative compounds which act as PTK blockers. PTK inhibitors which preferentially inhibit the epidermal growth factor (EGF) receptor kinase block EGF-dependent cell proliferation.{14963} RG-14620 is an inhibitor of epidermal growth factor (EGF) receptor kinase with an IC50 value of 3 µM in HT-22 cells.{14964}