ALDH1A1 and cancer: Moreover, in nasopharyngeal carcinoma, TB cells show high expression of the cancer stem cell (CSC) marker aldehyde dehydrogenase 1 (ALDH1), a cytosolic enzyme that promotes the intracellular oxidation of aldehydes and contributes to the oxidation of retinol to retinoic acid in the initial stages of stem cell differentiation [41].