SOX2 and cancer: In order to evaluate whether the isolated ALDH+ populations were enriched for cancer stemness, we examined the expression level of the pluripotency transcription factors such as SOX2, OCT4, and NANOG along with ALDH1A1 (one of the key isoforms in the ALDH family of enzymes regulating the cancer stem cell phenotype) by immunoblotting of total lysates from ALDH+-BCSCs.