STAT3 and lung cancer: Particularly, Zhao et al. discovered that metformin could inhibit IL-6-induced lung cancer EMT by blocking STAT3 phosphorylation [22], Han et al. found the metformin could suppress EMT of thyroid cells through inhibiting mTOR [24], and Banerjee et al. demonstrated that metformin can delay EMT development by interfering with Wnt signaling [41].