qPCR analysis for expression of well-characterized stemness genes revealed that A549 CSC cultures express elevated mRNA for many genes associated with the stem cell phenotype (27) including OCT3/4, ALDH1A1, NOTCH3, SOX2, NANOG, CDC133, and CD44 when compared with A549 BCC cultures (Fig. 2B; Supplementary Fig. S2B). The gene discussed is ALDH1A1; the disease is skin basal cell carcinoma.