Cannabinoids inhibit cancer cell proliferation, induce cancer cell apoptosis, and impair tumor angiogenesis in vivo. (A) Ki67-positive cells (red), (B) active caspase-3-positive cells (red), (C) CD31-positive cells (green) and (D) CD45-positive area in the tumors. Scale bars: A, 60 μm; B, 40 μm; C and D, 100 μm. Cell nuclei are in blue. Quantifications of Ki67-positive cells (A), active caspase-3-positive cells (B), the number of blood vessels (C) and CD45-positive area (D) in the tumors are shown in the corresponding graphs.