A population of CD44+/CD24−/low cells from breast cancer patients has been isolated and demonstrated to have tumor‐initiating and sustainability in 2003.8 Subsequently, a series of studies confirmed the presence of CSCs was in breast cancer.26, 27 CD44+/CD24−/low, aldehyde dehydrogenase 1 (ALDH1), Oct‐4, and Sox2 have been widely accepted as important and reliable surface markers for the isolation and identification of BCSC.23, 24, 28, 29 Initially, we isolated CD44+/CD24−/low cell subpopulation by MACS and analyzed stem cell characteristics in vitro. The gene discussed is ALDH1A1; the disease is breast cancer.