STAT3 and precursor B-cell acute lymphoblastic leukemia: XBP1 expression levels were under the control of BCR-ABL1 in Ph+ B-ALL subtype [122], whereas in Ph- pediatric B-ALL patients GRP78 was downstream of the Spleen tyrosine kinase (Syk)/Signal Transducer and Activator of Transcription 3 (STAT3) axis [123] (Figure 2).