Characterization of ALDH positive population in human NSCLC cell lines. A: H1299 and H460 cells stained for Aldefluor substrate present a positive population that is blocked by co-incubation with the specific inhibitor DEAB. B: Isolated H1299 ALDH+ cells possess self-renewal ability as shown by their capacity to generate both ALDH+ and negative populations after 10 days of culture, while negative cells only give rise to negative cells. C: MTT assay demonstrates a greater proliferative rate for ALDH+ cells as compared to the negative population, which reach statistical significance at 96 h. D: Isolation of both ALDH positive and negative cells present higher colony formation efficiency in soft agar than their negative counterpart. Data and error bars are presented as mean ± SEM; *: p < 0.05.