There was a significant accumulation of CXCR4-expressing MDSCs around colonic tumours (50- to 100-fold), along with increased expression of pro-tumorigenic cytokines IL-17A and IL-1β (Fig. 3b and Supplementary Fig. 6a–d), in Tff2-null and wild-type mice compared with CD2–Tff2 mice. The gene discussed is IL17A; the disease is colonic neoplasm.