<p>A549 cells were challenged with 100 μM heme for 24 hours and then stained with 5 μg/ml AO. <b>(A)</b> A549 cells deficient in intact lysosomes (‘pale’ cells) were measured by flow cytometry. <b>(B)</b> The summary of data shown in (A). Data are means ± SEM of 3 independent experiments. *p≤0.01. <b>(C)</b> A549 cells were pre-treated with 1 mM DFO for 2 hours and then challenged with 100 μM heme for 24 hours. Cell viability was measured using alamar blue. Data are means ± SEM of 3 independent experiments. *p≤0.05.</p