Representative dot plots indicating the frequency of endothelial cell apoptosis in Namalwa tumors generated in NOD/SCID mice.

Tumors dissolved as single cells were evaluated by flow cytometry. Panel A shows forward and side scatters of the cell suspension and the analysis gate, panel B the negative control, and panel C the human CD19⁺ phenotype of the tumor. As indicated by the percentage of murine cells positive for FLK and 7-amino actinomycin D (panels D and E), the frequency of endothelial apoptotic cells was significantly increased in mice given endostatin.