The proliferation and invasion assay confirmed that proliferation and invasion ability of DLD-1 colon cancer cells in the group transfected with CXCL12 siRNA were significantly inhibited compared with control siRNA group and untreated group, this indicated that CXCL12 siRNA could inhibit the proliferation (Fig. 3) and invasion (Fig. 4) of colon cancer cells with expression CXCL12, but there is no influence for HT-29, CaC0-2 and Colo320 cell, because they have not secretion of CXCL12. This evidence concerns the gene CXCL12 and malignant colon neoplasm.