IL9 and colorectal neoplasm: To determine the potential presence of Th9 cells in experimental colorectal we investigated the expression of IL-9 in the AOM/DSS model.32 Quantitative PCR analysis revealed a significant induction of IL-9 mRNA expression in isolated colorectal tumors from AOM/DSS treated wildtype [WT] mice as compared with untreated controls [Figure 2A, upper right panel].