ALDH1A1 and lung cancer: However, several studies have shown a strong positive association of ALDH1 with lung cancers, and inhibiting ALDH1 has led to the downregulation of stemness-related genes associated with lung cancer (Jiang et al., 2009; Leung et al., 2010; Gomez-Casal et al., 2013; Duan et al., 2014; Hardavella et al., 2016; Zakaria et al., 2017).