We analysed tumour cell death by staining for cleaved caspase 3 and found a higher percentage of dying cells in tumour slices after 24-h exposure to either microglial cells (20.6 ± 1.8%, mean ± S.E.M., N = 4) or macrophages (25.6 ± 2.2%) compared to control samples (4.5 ± 0.7%) (Fig. 5d). This evidence concerns the gene CASP3 and neoplasm.