<p><b>(A)</b> A549 cells were pre-treated with 5 mM 3-AT for 2 hours and then challenged with 100 μM heme for 36 hours. Cell viability was measured by alamar blue. <b>(B)</b> A549 cells were transfected with both 10 nM HO-1 and human catalase siRNAs for 24 hours and then challenged with 100 μM heme for 36 hours. Cell viability was measured by alamar blue. In both cases, data are means ± SEM of 3 independent experiments. *p≤0.05.</p
