ALDH1A1 and ovarian cancer: Figure 2(e) shows the ALDH1 expression was significantly reduced in ID8 cancer stem-like cell-immunized mice compared to ID8 noncancer stem-like cell-immunized mice (p < 0.0228, Figure 2(f)). It is therefore reasonable to conclude that the CSC vaccinations could reduce the CD44+CD117+ CSC and ALDH-positive cell subsets in ovarian cancer tissues.