The population of ALDH1-positive cells within M13SV1-EGFP-Neo breast epithelial cells was approximately 8.4 ± 2.5%, whereas ALDH1 expression was determined in approximately 2.8 ± 0.4% of HS578T-Hyg human breast cancer cells (Fig. 3). The gene discussed is ALDH1A1; the disease is breast carcinoma.