After its initial applications in leukemia (Storms et al. 1999) and breast cancer (Ginestier et al. 2007), ALDH+ population has been applied to identifying CSCs in many other cancer types, such as lung cancer (Sullivan et al. 2010), pancreatic cancer (Kim et al. 2011), colorectal cancer (Shenoy et al. 2012), and prostate cancer (van den Hoogen et al. 2010). The gene discussed is LDHA; the disease is lung cancer.