A reversible inhibitor of the auto and transphosphorylation kinase activity of the ErbB receptor tyrosine kinase superfamily: EGFR (IC50 = 8 µM), ErbB-2 (IC50 = 49 nM), ErbB3, and ErbB4 (IC50 = 52 nM); induces G1 cell cycle arrest in MCF10A breast cancer cells.