Deregulation of JAK/STAT signaling may also be due to JAK2 or EPOR rearrangements, or to additional alterations activating other JAK/STAT signaling genes (IL7R, FLT3, SH2B3, JAK1, JAK3, TYK2, and IL2RB), accounting for 8%, 4% and 12% of pediatric Ph-like ALL, respectively [24,30]. Here, JAK1 is linked to acute lymphoblastic leukemia.