Bosutinib, a potent inhibitor of the human nonreceptor tyrosine kinases Src and Abl (Fig. 2, A), was approved by US FDA in 2012 for treatment of adults with newly diagnosed chronic phase Philadelphia chromosome positive (Ph+) chronic myelogenous leukemia (CML) and chronic, accelerated, or blast phase Ph+ CML with resistance or intolerance to prior therapy. The gene discussed is SRC; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.