HMOX1 and neoplasm: Li et al. [26] reported that in a dithiothreitol (DTT) assay a quantitative measure of in vitro ROS formation correlated with HO-1 expression in the Abeison murine leukemia virus-induced tumor (RAW264.7) cell line exposed to ultrafine particulate pollutants, in the murine macrophage cell line, human bronchial epithelial cell (BEAS-2B cell) line, and in the human bronchial epithelial cell line.