JAK2 and precursor B-cell acute lymphoblastic leukemia: PAX5 rearrangements may occur with different partners, such as POM121, BRD1, DACH1, HIPK1 and JAK2 (PAX5-JAK2 rearrangement has been found in Ph-like ALL, leading to aberrant activation of JAK/STAT signaling pathway) and all these rearrangements are observed in approximately 11% of B-ALL childhood patients [73].