In conclusion, the study presented here proposes a novel mechanism of breast cancer progression by which aberrant activation of the Aurora-A/SMAD5 oncogenic axis induces expression of CD44 and PROCR receptors and increased ALDH1 activity that are critical to maintain a cancer stem cell-like phenotype responsible for chemoresistance and tumor progression (Figure 7). The gene discussed is ALDH1A1; the disease is neoplasm.