ALDH1 protein expression differs among normal ovary, benign tumors and malignant tumors. [A] The number of ALDH expressing cells was significantly lower in malignant tumors than in normal ovary and benign tumors. The boxplots represent the median (dark horizontal line), range (whiskers), and 25th-75th percentile (box) for each group (n = 5/group). Quantification of ALDH1+ cells was performed using StereoInvestigator software. [B] Protein was detected in tissue homogenates by Western blot (10 μg protein/lane). A single immunoreactive band reacted with mouse anti-ALDH1 (upper panel). Recombinant ALDH1 (1 μg; lane 16) was used as a positive control. Human actin was used as a loading control (lower panel). Densitometry analysis confirmed differential ALDH1 protein expression in ovarian tissues. Each sample was plotted on Y-axis as ratio of the relative density of ALDH1 normalized to actin.