In vitro treatment with IL-33 enhanced sphere formation by primary human CRC cells and HT29 cell line, with a concomitant increase in expression of stem cell markers NANOG, NOTCH3, OCT3, OCT4 and LGR5 resulting in treatment resistance against 5-fluorouracil in a ST2-dependent manner (94). Here, IL1RL1 is linked to colorectal carcinoma.