Abstract: objective To investigate the role of ST3GAL4 in proliferation and c-met signaling of human breast cancer cell line MDA-MB-231. Methods Three different siRNAs were designed to knock down ST3GAL4 according to its coding region. The expression of ST3GAL4 in mRNA and protein level was examined by RT-PCR and Western blot. Then colony formation assay and c-met phosphorylation of MDA-MB-231 were analyzed after knocking down of ST3GAL4. Results After transfection for 40 hours, the intracellular level of ST3GAL4 mRNA and protein were lower than those in control group (siNC). Ability of colony formation of MDA-MB-231 was significantly weakened, compared with control group (p<0.05). Moreover, activation of c-met pathway was inhibited. Conclusions ST3GAL4 may be involved in the proliferation and c-met signal pathway of MDA-MB-231.