ALDH1A1 and neoplasm: In line with previous reports, we showed that chronic CSE exposure increased colony formation, induced epithelial-mesenchymal transition-like changes, increased the expression of lung CSC markers (CD133, ALDH1A1, Oct4, and Nanog), and increased in vivo tumor incidence, suggesting that TS promotes CSC-related traits in human bronchial epithelial cells.