ALDH1A1 and breast cancer: Using HER2-overexpressing BT-474 cells as a breast cancer model naturally enriched with ALDH1+ cells (>50%), we detected a decrease in the proportion of ALDH1+ cells following 72 h treatment with increasing concentrations of iadademstat (up to 35% decrease at 25 μmol/L iadademstat) as compared with vehicle-treated controls (Figure 3B).