For example, the STAT3 activated by IL-17 or IL-6 can facilitate cancer cell angiogenesis, migration, invasion and metastasis via increasing the expression of vascular endothelial growth factor (VEGF), O-GlcNacylation, MMP or the switch of epithelial-mesenchymal transition (EMT) to mesenchymal-epithelial transition (MET) [19–23]. The gene discussed is IL17A; the disease is cancer.