Interestingly, we were unable to demonstrate that constitutive ASM-derived IL-33 was sufficient to induce IL-13 release from mast cells in coculture, and therefore, it is likely that either upregulation of IL-33 release by ASM in vivo or contributions from other cellular sources such as the epithelium might be important in activating IL-13 release from mast cells in asthma. This evidence concerns the gene IL33 and asthma.