CA4P induces leukemic cell death in vivo. NOD-SCID mice bearing established xenotransplanted HL60 tumors were treated every day for 3 days with intraperitoneal injection of CA4P (10, 25, or 50 mg/kg), and compared with the control group, which received PBS. (A) CA4P induces leukemic cell death and targets neovessels. HL60 tumors were removed and photographed, and tumor sections were stained with hematoxylin and eosin for histologic analysis. Cell death was assessed by TUNEL assay. Red staining represents positive signal within the tumors (blue cells are negative [ie, viable] cells). Tumor neovessels (yellow arrows) were identified by MECA-32 staining. All photomicrographs: original magnification, 10×; scale bar equals 50 μm. (B) Quantification of the microvessel density in HL60 tumor sections. The microvessel density was evaluated by microscopic counting of 5 fields at 10× magnification, and presented as mean number of microvessels per microscopic field plus or minus SEM (*P < .05 compared with the PBS control group; n = 5).