While Z-119 expresses the BCR-ABLp190 isoform, which accounts for approximately two thirds of Ph+ ALL cases, BV-173 features the BCR-ABLp210 isoform that is found in the remaining Ph+ ALL patient population, as well as in CML [11]. The gene discussed is BCR; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.