ALDH1A1 and cancer: Cellular RR in isogenic cell lines was confirmed by changes in cell morphology, clonogenic survival, enrichment of side-population and cancer stem cell markers (ALDH1, CD133, OCT3/4, ESA, and, β-catenin), pronounced G2/M arrest coupled with the accumulation of cell cycle regulator (cyclin D1 and Cyclin E) along with enrichment of FDPS, and measurable in vivo tumour growth with respect to matched parental cells (Figures. 1f and g; S2a–e).