Figure S7 shows that this was indeed the case: murine tumour cells resistant to genotoxic insult at physiological pHi values can be sensitised to die by enforced alkalinisation leading to Bcl-xL deamidation. Furthermore, a modest rise in pHi following incubation in a mildly alkaline buffer produces levels of Bcl-xL deamidation and apoptosis in murine tumour cells comparable to those observed by adding a DNA damaging reagent to wild-type thymocytes incubated at physiological pH. This evidence concerns the gene BCL2L1 and neoplasm.