Imatinib is the first receptor tyrosine kinase (RTK) inhibitor with activity against ABL, BCR-ABL, PDGFR, and c-KIT [29], and is the standard of care in chronic myelogenous leukemia (CML), GIST, DFSP, and various other cancers [29]. The gene discussed is PDGFRB; the disease is gastrointestinal stromal tumor.