Effect of hemin on HN33 cell viability.

HN33 cells were treated with hemin for 24 hours at the indicated concentrations (panel A) or at 50 μM for the indicated times (panel B), and viability was measured with MTT. Results (mean ± SEM from 3 experiments) are expressed as a percentage of viability in untreated control cultures. Only treatment with 100 μM hemin produced a significant (P < .05) difference in viability compared with controls.