We treated three B-ALL cell lines with ruxolitinib (a JAK1/JAK2 inhibitor), fedratinib (a type I selective JAK2 inhibitor), and CHZ868 (a type II selective JAK2 inhibitor) to evaluate the effect of JAK inhibitors on B-ALL cell lines with varying JAK2 mutation statuses. The gene discussed is JAK2; the disease is acute lymphoblastic leukemia.