ALDH1A1 and lung cancer: Not surprisingly, several ALDH isoforms other than ALDH1A1 have been proved being associated with certain cancers, e.g., ALDH3A1 in lung cancer (Patel et al. 2008) and prostate cancer (Yan et al. 2014) and ALDH5A1 in breast cancer (Kaur et al. 2012).