ALDH1 mRNA expression differs among normal ovary, benign tumors and malignant tumors. ALDH1 mRNA levels determined by qRT-PCR were significantly lower in malignant tumors than in normal ovary and benign tumors. ALDH1 mRNA did not significantly differ between benign tumors and normal ovary. Values for ALDH1 were normalized to actin as an internal control. The boxplots represent the median (dark horizontal line), range (whiskers), and 25th-75th percentile (box) for each group (n = 5/group).