STAT3 and cancer: Once STAT3 is activated, two monomeric STAT3 form homodimers or heterodimers via the tyrosine residue 705 reciprocally interact with the SH2 domain and subsequently translocate into the nucleus and regulate genes expression which are involved in sustaining proliferation [13], metastasis [14], angiogenesis [15], inflammation [16], resisting apoptosis [17], immune suppression [18], tumor microenvironment [16], cancer stem maintenance [19], and reprogramming metabolism [20], drug resistance [21] and exosome mediation of cancer hallmarks activities [22].