BCSCs have been investigated in primary tumours, cell lines and mouse models using various markers, including CD44/CD24 [4, 6], CD133 [11], ITGA6 [12] and high expression [7] or activity [7, 13] of aldehyde dehydrogenase 1 (ALDH1) as assessed by Aldefluor assays. Here, ALDH1A1 is linked to neoplasm.