In breast cancer, mixed results have been reported regarding the specific ALDH1A isoenzyme involved in tumorigenesis and the ALDEFLUORTM assay, with some groups reporting ALDH1A1 as the main enzyme involved and others showing that ALDH1A3 is the accountable isoform [9, 10, 61, 62]. The gene discussed is ALDH1A1; the disease is breast carcinoma.