Increased aldehyde dehydrogenase (ALDH) activity has been associated with CSCs in several cancers [41], including neuroblastoma [42], where ALDH activity and expression of certain ALDH isoforms (i.e., ALDH1A2, ALDH1L1, ALDH3B2) were associated with sphere and colony formation [42]. Here, ALDH1A2 is linked to neuroblastoma.