Besides, Han et al. developed M@H-NPs using hyaluronic acid-based nanoparticles to load minoxidil, which can target brain metastatic tumors.152 Hyaluronic acid can specially target cell surface receptor CD44, which is highly expressed in breast cancer.153 With the help of the CD44 target and MS boost, M@H-NPs could penetrate blood–brain tumor barrier (BTB), internalizing into brain metastatic tumor cells (BMTCs), blunting drug efflux at BMTCs, and producing effective treatment which can extend the median survival time in breast cancer brain metastases models. This evidence concerns the gene CD44 and breast cancer.