Aldefluor assay and the expression of ALDH1 and Notch signaling genes in ovarian cancer stem cells. A. ALDH1 population in primarily-cultured human ovarian carcinoma cells was analyzed by Aldefluor assay. DEAB is a specific inhibitor of ALDH and was used to confirm gating areas. ALDH1 (+) population (6.74%) was displayed in the absence of DEAB. B. Expression of ALDH1 mRNA in parental carcinoma cells and spheroid forming cells from 5 primarily-cultured ovarian carcinoma cells (SCN 1-5). C. The mRNA expression of Notch signaling genes in FACS-sorted ALDH1 (+) ovarian cancer cells. Notch3 (1.8-fold, p = 0.046), Notch1 (1.2-fold, p = 0.007), and Hes1 (1.2-fold, p = 0.033) were significantly overexpressed in ALDH1 (+) cells compared with ALDH1 (-) cells.