JAK1 and acute lymphoblastic leukemia: Ruxolitinib, the first JAKinib approved by the United States Food and Drug Administration (FDA), is a potent inhibitor of JAK1 and JAK2, used for primary myelofibrosis (O’Shea et al., 2015) and its effects have been also studied in MDS, AML, ALL, chronic myelomonocytic leukemia (CMML) and chronic myeloid leukemia (CML) (Eghtedar et al., 2012; Pemmaraju et al., 2015).