In oral cancer, several approaches have been employed to enrich and isolate CSCs, such as sphere formation [5], cell surface expression of specific stem cell markers (e.g., CD44) [6], increased enzymatic activity (e.g., aldehyde dehydrogenase, ALDH1) [7] or efflux of vital dyes by multi-drug transporters (e.g., ABC transporters) [8]. This evidence concerns the gene ALDH1A1 and lip and oral cavity carcinoma.