Figure 6. 91R promotes apoptosis and necrosis and reduces cell proliferation and angiogenesis in tumor xenografts. (A-D) Histological analysis of xenografted MOLT-4 tumors (n = 5 mice/group). (A) Hematoxylin/eosin-stained sections from xenografted MOLT-4 tumors treated with 91R or control IgG2b mAb; bar = 2 mm. Right, images at higher magnification; bar = 25 μm. (B) Graph shows percentage of tumors classified by necrotic stage (< 1%, 1–30% and > 30%). Chi-square test, ***P < 0.0001. (C) Apoptosis level in tumors was analyzed by TUNEL assays. Proliferation levels were determined by PCNA immunostaining. Blood vessels were detected by CD31 staining. Tissue sections were DAPI-counterstained. Bar = 50 μm. (D) Quantitative analyses of TUNEL- and PCNA-positive nuclei and vessels per optical field. Mann-Whitney test, *** P < 0. 001, ** P < 0. 01, * P < 0.05.