Although we compared only two pairs of OS cell types with non-metastatic versus metastatic potentials, CCL2 was identified as a factor commonly secreted by metastatic LM8 and 143B cells (Fig. 2), and treatment with a CCL2-neutralizing antibody suppressed lung metastasis in orthotopic LM8 and 143B tumor model mice (Fig. 5), suggesting CCL2 plays a crucial role in promoting lung metastasis of OS cells. The gene discussed is CCL2; the disease is neoplasm.