Various tyrosine kinase inhibitors (TKIs) for BCR/ABL, such as imatinib, nilotinib, and dasatinib, have been in clinical use and have demonstrated unprecedented efficacy for treatment for Ph-positive leukemias, whereas the JAK1/JAK2 inhibitor ruxolitinib has been approved for clinical use against myeloproliferative neoplasms with only limited efficacies. The gene discussed is BCR; the disease is myeloproliferative disorder.