IL6 and neoplasm: Once binding to IL-6 receptor (IL-6R) and gp130 receptor, IL-6 could activate STAT3, mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) pathways and increase tumor metastasis [43–44, 51], indicating that IL-6 increasing metastasis is IL-6R/gp130 dependent.