SNAI1 and cancer: Cancer-associated fibroblasts play important roles in tumor growth and maintenance through secreting autocrine and paracrine signaling molecules such as IL-1α, IL-1β, IL-6, IL-33, HGF, VEGF, TNF-α, TGF-β, CCL-2, CXCL-12, CXCR-4, MMP-2, and Snail (17, 19, 22).