Evidence suggests that breast cancer cells exhibiting high ALDH activity are associated with poor prognosis and late-stage tumors (Charafe-Jauffret et al., 2010; Marcato et al., 2011); ALDH is now also considered as a CSC marker for other types of cancers (Jiang et al., 2009; Li et al., 2010; Pearce et al., 2005). The gene discussed is LDHA; the disease is breast cancer.