The cases studied by Kamihara et al. [42] indicated that CXCL12 (SDF-1)/CXCR4 axis is involved in the observed metastasis of diffuse large B cell lymphoma to primary STAD and considered that the interaction between chemokines and their receptors may be the potential mechanism of the observed metastasis between tumors. The gene discussed is CXCL12; the disease is gastric adenocarcinoma.