Overexpression of TREM2 inhibits CRC progression by negatively regulating the Wnt/ERK/GSK-3β signaling pathway (Figure 3), as well as inhibiting CRC cell proliferation, invasion, and metastasis by down-regulating the expression of cyclin D1 and MMP9 (matrix metalloproteinase 9) (56). The gene discussed is MMP9; the disease is colorectal carcinoma.