Figure 3. Iadademstat inhibits stemness-associated SOX2 expression in a luminal-B/HER2+ established cell line. (A) Schematic representation of SOX2 promoter structure indicating the proximal core promoter region and the location of the distal enhancer, which is induced exclusively upon CSC-driven mammosphere formation but not in cell-adherent differentiating conditions. Results are expressed as fold-induction of mammosphere culture-associated SOX2 reporter activity above adherent culture control in the absence or presence of graded concentrations of iadademstat. The results are expressed as percentages means (columns) ± SD (bars). *P < 0.05 and **P < 0.005, statistically significant differences from the untreated (control) group. (B) Representative Aldefluor® assay to identify BT-474 cells with high ALDH activity (ALDH+) in the absence or presence of graded concentrations of iadademstat for 3 days. The ALDH inhibitor diethylaminobenzaldehyde (DEAB) was used as negative control. Monolayer cultures were fed with iadademstat on day 1. (Note: 1 μmol/L FM19G11, an epigenetic repressor of key genes involved in stemness including SOX2 , was employed as a positive control).