To resolve this controversy, we recently reinvestigated the role of METCAM in the tumorigenesis of human breast cancer cells in animal models and found that overexpression of METCAM promoted the tumorigenesis of four human breast cancer cell lines, MCF7, SK-BR-3, MDA-MB-231, and MDA-MB-468 [30, 31]. This evidence concerns the gene MCAM and breast cancer.