IL1RL1 and neoplasm: Given that the less malignant 3LL cells express functional ST2L and that IL-33 is highly expressed in less malignant tumours, coinciding well with the gene expression profiles in human lung adenocarcinomas (Figure 1A; Supplementary Figures 1 and 2), we hypothesised that IL-33 might affect the phenotypes of cells under conditions that mimic the tumour microenvironment, such as nutrient depletion and hypoxia.