STAT3 and neoplasm: Apart from this, CD39 and CD73 enzymes, which are the downstream targets of STAT3 signaling, coordinately dephosphorylate adenosine triphosphate (ATP) to form adenosine, thus promoting tumor cell metastasis (Mittal et al, 2016; Stagg et al, 2010) and also angiogenesis (Allard et al, 2014).