MMP1 and neoplasm: Our results are consistent with the other study showing DEPs increased MMP-1 activation based on an NADP(H) oxidase–dependent pathway (for the relevance of DEPs evoking oxidant-mediated injury, see Amara et al. 2007; Bayram et al. 2006; Cao et al. 2007b; Ghio et al. 2000; Madden et al. 2000; Zhang et al. 2004; for using tumor-derived alveolar cells, see Amara et al. 2007).