IL-33 and ST2 are expressed in a variety of cells, including epithelial cells, stromal cells, infiltrating lymphocytes and microvessels (19), and IL-33 and ST2 at the mRNA level of whole CRC specimens quantified by real-time PCR may not differentiate the expression level of IL-33 and ST2 in various compartments of the tumor microenvironment. This evidence concerns the gene IL1RL1 and neoplasm.