Interestingly, several metastasis-related genes, including PLAU and PLA2G7, were found to be highly induced in monocytes/macrophages, but not in C666-1 cells (Figures 5 and S4), indicating that NPC cells are able to change the phenotype of macrophages to promote tumor metastasis. This evidence concerns the gene PLAU and nasopharyngeal carcinoma.