The CXCR4 receptor is highly expressed on MDSC from blood and colonic tumour tissues from CRC patients25 and TFF2 binds to and acts through the CXCR4 receptor26, 27, 28, 29, CXCR4 expression on splenic CD11b+Gr-1+ cells was increased in DSS-treated and in tumour-bearing mice (Supplementary Fig. 8i,j). The gene discussed is TFF2; the disease is colorectal carcinoma.