CXCL16 and metastatic neoplasm: The two-color immunofluorescence staining with anti-CXCL16 and anti-EpCAM mAb and consecutive-sections-staining procedure with anti-CEA and anti-CXCL16 in the primary tumor tissues and lymph node metastasis suggest that CXCL16 is produced mainly by primary tumor cells and metastatic tumor cells.