The association of low claudin expression with resistance to chemotherapy is supported by a recent study showing that subpopulations of CD44+/CD24−/low breast cancer cells with high CSC/TIC potential and a claudin-low subtype are enriched in residual tumors after conventional chemotherapy, which is in line with the expectation of survival of CSC/TICs after treatment [17] and indicates that the claudin-low subtype of breast cancer is associated with increased resistance to chemotherapy. The gene discussed is CD44; the disease is breast cancer.