Complementing tumor ALDH1a3, ALDH1a2 is found in the cancer stroma, such as the immunoregulatory mucosal myeloid regulatory DCs found in lung cancer patients (Maier et al., 2020) or the M2 macrophages in glioblastoma that promote tumor tolerance (Sanders et al., 2021). This evidence concerns the gene ALDH1A3 and lung cancer.