IRF8 and neoplasm: In these models, we observed that Il9 mRNA expression and IL-9 protein secretion were reduced in tumour-infiltrating CD4+ T cells (TILs) or in CD4+ T cells from tumour-draining lymph nodes (TDLN) of Irf8f/fCd4cre mice compared to those of WT or Irf8+/+Cd4cre mice (Fig. 6c–e).