The expression of DDB2 protein, but not DDB2 mRNA, is reduced in ovarian CSCs. A to D, the protein level of DDB2 in various CSCs and their parental bulk cancer cells was determined using immunoblotting with anti-DDB2 antibody. The stem cell marker Nanog was also detected to show the CSC property. E to H, the mRNA level of DDB2 in various CSCs and their parental bulk cancer cells was determined using quantitative RT-PCR. The stem cell marker Nanog was also detected to show the CSC property. Bar, SD; n = 3; **, P < 0.01 compared with bulk cancer cells.