CD24 and neoplasm: Importantly, treatment with mouse IgG1 isotype control did not induce phagocytosis of CD24high cell lines (Supplementary Figure S2E), nor did treatment of tumor cells alone with CD24 mAb induce apoptosis as measured by phosphatidylserine (PS) exposure [44], even upon cross-linking with a secondary anti-mouse antibody, within the time frame of the phagocytosis experiment (Supplementary Figure S2F).