MCAM and melanoma: We initiated the investigation by comparing the expression of METCAM/MUC18 in four human breast cancer cell lines, MCF7, SK-BR-3, MDA-MB-231, and MDA-MB-468 to cell lines whose levels of METCAM/MUC18 expression are well-characterized: the human melanoma cell line SK-Mel-28, which highly expresses METCAM/MUC18; the prostate cancer cell line DU145, which moderately expresses METCAM/MUC18; and the prostate cancer cell line LNCaP, which does not express METCAM/MUC18.