GREM1 and breast cancer: When we examined the GREM1 expression in 52 human breast cancer cell lines by mining previously published datasets (see the “Methods” section), we found that only 3 breast cancer cell lines express low (MDA-MB-436 and HCC38) or intermediate (SUM149PT) levels of GREM1; all other 49 cell lines had no detectable expression (Fig. 1b).