MCAM and nasopharyngeal carcinoma: Taken together, we concluded that the over-expression of huMETCAM/MUC18 in the NPC-TW01 cells suppressed the tumor formation induced by the cells, supporting the notion that huMETCAM/MUC18 plays a tumor suppressor role in the development of NPC-TW01 cells, which were established from type I NPC [37,38].