SLC5A8 and breast cancer: One of the marker genes, SLC5A8, a tumor-suppressor gene, was previously found to be hypermethylated in colon neoplasia,51 and the downregulation of SLC5A8 caused by aberrant DNA methylation was observed in breast cancer cells.52 The remaining three genes, RAB3C, GABRA2, and ZNF257, have not been reported to be associated with cancers, and further investigation of their biological functions is needed.