The proportion of CD44+CD24− cell subsets in the serum‐free suspension culture of MCF‐7‐CSC was significantly higher than that of MCF‐7 (P < 0.05) (Figure 1B), indicating that the presence of surface markers of breast cancer stem cells in MCF‐7‐CSC had increased significantly than that of in MCF‐7. Here, CD24 is linked to breast cancer.