Imatinib’s efficacy in CML relies on the inhibition of BCR-ABL protein kinase; however, it is a nonselective, multikinase inhibitor of BCR-ABL, platelet-derived growth factor receptor (PDGFR), and Kit protein-tyrosine kinases. This evidence concerns the gene PDGFRB and chronic myelogenous leukemia, BCR-ABL1 positive.