FACS analysis of tumours that were immediately initiated by NCAM+ALDH1+ cells revealed approximately 20% of ALDH1+ cells (higher percentage than unsorted p-WT Xn cells which contained 4–10% ALDH+ cells) and a large fraction of ALDH1− cells supporting the differentiation capacity of injected ALDH1+ cells. This evidence concerns the gene ALDH1A1 and neoplasm.