The BCR-ABL translocation product in chronic myelogenous leukemia (CML), the anaplastic lymphoma kinase (ALK) mutation in lung cancer and the BRAF V600E mutation in melanoma are prime examples of specific subsets of cancers that are exquisitely sensitive to rationally selected molecularly targeted antitumor agents [4]–[6]. The gene discussed is BCR; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.