CD44 and neoplasm: Taking advantage of the overexpression of the hyaluronic acid (HA)-binding receptors such as cluster determinant 44 (CD44) on the surface of malignant cells, which are known to bind HA glycans, HA-functionalized smart MWCNTs were developed as anticancer drug nanocarriers to encapsulate doxorubicin (DOX) for targeted delivery to cancer cells overexpressing CD44 receptors107–110 or as tumor-targeting MRI contrast agent when combined with Gd3+.