MMP9 and neoplasm: Tumor cells affect the recruitment of CAF precursors and induce normal fibroblasts to differentiate into CAFs, which secrete a variety of growth factors such as TGF-β, VEGF, chemokines and cytokines, such as CXCL12 (SDF-1), CXCL14, CXCL16, CCL2, CCL5, IL-4, and IL-6, and metalloproteinases, such as MMP-1, MMP-2, MMP-3, MMP-9, MMP-13 and MMP-14.