To understand the role of IL-33 in the tumours composed of low- and high-metastatic cells, we cultured a 1 : 1 mixture of EGFP-P29 and DsRed2-A11 cells under severe conditions (glucose depleted, hypoxic and serum depleted; GlucL/H/FBSL), similar to those that would be generated in the tumour microenvironment. The gene discussed is IL33; the disease is neoplasm.