The results from the analysis of six breast cancer cell lines and two normal breast epithelial cell samples (Additional file 2) indicated that 7 of 12 genes (RIL, HIN-1, RASSF1A, ARHI, CDH13, RARβ2, and NKD2) were densely methylated (marked bold) in cancer cell lines but not in normal breast epithelial cell lines. This evidence concerns the gene RASSF1 and breast cancer.