ALDH1A1 and lung cancer: Aberrant expression of CSC markers is associated with the initiation and development of lung cancer, including cluster of differentiation 133 (CD133), Musashi RNA-binding protein 1 (Musashi-1), aldehyde dehydrogenase 1 (ALDH1), epithelial cell adhesion molecule (EpCAM), B-cell-specific moloney murine leukemia virus integration site 1 (Bmi-1), Octarner binding factor 4 (OCT-4), and Glycine dehydrogenase (GLDC) [12]–[20].