IL1RL1 and neoplasm: FOXP3+ Tregs exhibit phenotypic plasticity and provide a source of IL-17 in CRC.27 IL-17 contributes to intestinal tumorigenesis in mice since genetic ablation of Il17a leads to decreased AOM/DSS-induced CRC.28 Our transcriptomic analysis revealed that genes from the ontology pathway “Th17 cell differentiation” were differentially expressed in ST2+ versus ST2− tumor-derived CD4+ FOXP3+ T cells (Fig. 4b and Supplementary Table 1).