STAT3 and cancer: The underlying mechanism of Piwil2 in tumorigenesis may differ among various cancer cells, such as anti-apoptosis by activation of the Stat3/Bcl-XL pathway [9], suppressing P53 expression by enhancing Stat3 phosphorylation [16], promotion of proliferation via the Stat3/cyclin D1 pathway [9, 10], or increasing c-Myc expression by facilitating NME2 binding to the G4-motif [5].