ALDH1A1 and breast cancer: In addition, breast cancers with low ALDH1 expression in their biopsies obtained prior to chemotherapy had higher percentage of apoptotic cells and lower percentage of proliferating cells in the corresponding surgical specimens obtained after neoadjuvant chemotherapy (Figure 1B, p<0.001), suggesting that ALDH1 expression in breast cancers is reversely correlated with apoptosis and proliferation inhibition induced by chemotherapy.