in August 2011, the United States FDA approved crizotinib (PF- 02341066) for the treatment of anaplastic lymphoma kinase (ALK) rearranged non-small-cell lung cancer (NSCLC). Crizotinib is a dual ATP competitive inhibitor of tyrosine kinases c-MET (Mesenchymal-Epithelial Transition Factor) kinase (cellular IC₅₀=8 nM) and ALK (cellular IC₅₀=20 nM), both of which are important targets for cancer chemotherapy. When crizotinib was tested for selectivity versus other kinases it was found to have enzyme IC_50's within 100-fold multiples of c-MET for 13 of the 120 kinases tested. In cellular assays, crizotinib was found to inhibit RON (recepteur d'origine nantais) kinase with a 10-fold selectivity window over c-MET.