In MDA‐MB‐231 cells, the decreased PAI‐2 could contribute to the increased tPA, uPA, and plasmin activity induced by ALDH1A3; however, given its absence in MDA‐MB‐436 cells, its role in ALDH1A3‐mediated plasmin activity in the breast cancer cells may be less important. This evidence concerns the gene ALDH1A3 and breast cancer.