In the MCF-7 ALDH1A1KD tumors, Ki67 staining was detected in 10–30% of tumor cells (+), whereas it was 70% in ALDH1A1+ or Scr tumors (+++) (Additional file 5: Figure S3) indicating that high proliferative activity was associated with ALDH1A1 expression in tumors. This evidence concerns the gene ALDH1A1 and neoplasm.