MTSS1 (metastasis suppressor 1), a downstream target of DNMT3B, was found to function as a tumor suppressor in HCC by Fan et al. [25] In line with this finding, our study shows the repression of DNMT3B accompanied with elevation of MTSS1 by fucoidan inhibits growth and invasion activities of HCC cells. The gene discussed is DNMT3B; the disease is hepatocellular carcinoma.