CD44 and neoplasm: Figure 3C showed that the tumor volume at the end of 90 days was significantly increased in the RT-R-MDA-MB-231 group. In addition, immunohistochemistry (IHC) staining revealed that RT-R-MDA-MB-231 xenograft tissue showed a significantly higher expression of CSC markers, such as CD44, Notch-4, and Oct3/4 (Figure 4).