MMP9 and esophageal squamous cell carcinoma: Because EMT activates the secretion of MMPs from tumor cells to facilitate the degradation of the basement membrane and promote cell invasion [37], we further examined the secretion profiles of MMPs induced by TAM-derived CCL22 using ELISA and found that pol-TAMs, pri-TAMs, or CCL22 (50 ng/ml) effectively stimulated the secretion of MMP-2, MMP-3, MMP-9, or MMP-13 from the indicated ESCC cells.