Imatinib mesylate, a small-molecule tyrosine kinase inhibitor that targets Abl kinase activity associated with the Bcr-Abl translocation found in chronic myelogenous leukemia (CML) also blocks the activity of PDGFR, c-kit and c-fms (also known as colony stimulating factor 1 receptor or CSF1R). The gene discussed is KIT; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.