CCL4 and cancer: Based on the mast cell activation gene expression signature derived from our in vitro mast cell stimulation with IL-33, we analyzed a publically available data set (DErrico Gastric data set; GEO: GSE13911) for differential expression of the mast cell signature comprising CCL2, CCL3, CCL4, IL1a, IL4, IL6, IL13, CSF2, and CCL7. With the exception of IL-4 and IL-13, we found that all other factors were at least 1.6-fold increase in the cancer samples (p ≤ 0.05) (Fig. 8a).