In the same way, we found that COL4A1 silence downregulated the expressions of Ki67, PCNA, MMP2, MMP9, N-cadherin and Vimentin but promoted E-cadherin expression in MKN-45 cells, revealing that COL4A1 silence could help to suppress the proliferation, metastasis and EMT in gastric cancer. This evidence concerns the gene MMP9 and gastric cancer.