Recent data have suggested that blocking of Pak1 upstream activators may also be beneficial by indirectly blocking Pak activity. Growth factor-induced activation of Pak1 can be inhibited by the PDGF-R-specific inhibitor AG1478 or by the EGF receptor-specific inhibitors (Iressa), monoclonal antibody 225, or the HER2 blocker trastuzumab (Herceptin). P21-activated kinase 1 (PAK1) inhibitor library in Otava contains 606 compounds.