a, Caspase activities of lysates of HeLa cells treated with the indicated compounds for 18 h were measured by using 200 μM acetyl-DEVD-pNA in the absence (grey bars) and presence (black bars) of 20 μM Ac-DEVD-CHO (mean ± s.d., n = 3). b, HeLa cells were treated with the indicated compounds for 18 h. Immunoblotting was conducted using the corresponding antibodies. β-Actin was used as a loading control. c, HeLa cells pretreated with 10 μM SBFI-AM were incubated with 10 μM of the indicated compounds for the indicated times. The SBFI-AM fluorescence was then measured to probe changes in the intracellular sodium ion concentration (mean ± s.d., n = 3). d, HeLa cells pretreated with 10 mM MQAE for 1 h were incubated with 10 μM of each compound for the indicated times. The MQAE fluorescence was then measured to determine changes in the intracellular chloride ion concentration (mean ± s.d., n = 3). e, Flow cytometry of HeLa cells treated with 10 μM 3 for the indicated time and then stained with JC-1 (left) or fluorescein-annexin V (right).