In line with Goa et al. [8], who found that overexpression of Dand5 in the 4TO7 mouse mammary tumor cell line inhibits lung-derived BMPs and thereby promotes metastases in the lungs, we observed a reduction in lung metastases after injection of 66cl4 Grem1 depleted cells into the tail vein of nude mice. This evidence concerns the gene GREM1 and breast cancer.