Cells were then
incubated with purified WT VacA or purified VacA 6-27 or with serial dilutions
of H. pylori supernatant containing WT VacA or VacA-G14A. Cell viability was
assessed using the CellTiterAQueous One Solution cell proliferation assay (Promega)
according to the manufacturer’s instructions. As a control, cells were
treated with 1 M staurosporine (Cell Signaling), an agent known to cause
apoptosis, for various time intervals, and cell viability was assessed as described
above.