Figure 3. Antiapoptotic effects of argon and xenon. (A and B) Wild-type human osteosarcoma U2OS cells were left untreated or treated with 1 µM staurosporine (STS), 50 µM Z-VAD-fmk (Z-VAD), or both in control atmospheric conditions (N2) or in the presence of gas mixtures, in which N2 was specifically replaced with Ar or Xe, for 8 h. Thereafter, cells were processed for the cytofluorometric assessment of apoptosis-related upon DiOC6(3)/propidium iodide (PI) co-staining. Representative dot plots are depicted in (A), while quantitative data are in (B). In (B), black and white column illustrate the percentage of dead (PI+) or dying (PI-DiOC6[3]low) cells, respectively (means ± SD). *P < 0.05 (Student t test), as compared with untreated cells maintained in control atmospheric conditions. #P < 0.05 (Student t-test), as compared with cells treated with STS in control atmospheric conditions; ns, non significant (Student t test), as compared with cells treated with STS and Z-VAD in equal atmospheric conditions.