GDF15 and cancer: This AKT/ERK pathway can be triggered by multiple factors derived from TAMs or cancer cells themselves, involving the FGF2/FGFR1 signaling we mentioned above (39), growth differentiation factor 15 induced in TAMs and derived from cancer cells (possibly through TGF-β type II receptor) (39, 44), overexpression of ANXA10 by cancer cells interacting with CD204+ TAMs (41), and high CXCL8 expression in TAMs and cancer cells (through the CXCL8-CXCR1/CXCR2 axis) (42), which are closely correlated with tumor invasion depth, lymph node metastasis and poor prognosis and OS of ESCC patients.