STAT3 and cancer: In tumors, aberrant STAT3 activation can occur by canonical signaling where STAT3 monomers are phosphorylated at Tyr705 or by a noncanonical pathway or noncanonical pathway of STAT3 signaling where STAT3 is phosphorylated at serine 727 of STAT3 by mitogen-activated protein kinase, c-Jun N-terminal kinase or protein kinase C [7], which suggests that STAT3 is a promising target for cancer therapy [8].