GREM1 and breast cancer: GREM1 is overexpressed in human tumours, including carcinomas of the colon, lung, ovary, sarcoma, and pancreas.19–21 According to multiple microarray-based studies, the level of the GREM1 gene expression was found to be highly elevated in breast tumours and tumour stroma.4,22–25 However, the functions of GREM1 in breast cancer progression and underlying mechanisms remain largely unresolved.