CD24 was initially identified as a negative marker for CSCs in breast cancer (Al-Hajj et al., 2003), but has more recently been described as a positive CSC marker in lung cancer (Lau et al., 2014), colorectal cancer (Yeung et al., 2010), and triple-negative breast cancer (Azzam et al., 2013). The gene discussed is CD24; the disease is breast cancer.