CASP7 and neoplasm: RLS40 tumour tissue was initially characterised by a certain level of spontaneous apoptosis: the volume density of caspase-7 positive cells was 5.3 ± 0.5% of the total tumour tissue (Figure 4C and Table 1) and that of caspase-3 was 2.5 ± 0.3% (Figure S1).