NDRG2 also suppresses matrix metalloproteinase-9 (MMP-9) expression through the induction of BMP-4 secretion [31] and inhibits NF-kappaB activity and MMP-2 and -9 secretion [7], which abrogates the metastatic potential of breast cancer and fibrosarcoma cells. This evidence concerns the gene NDRG2 and breast cancer.