PECAM1 and fibrosarcoma: In spite of significantly smaller tumors in the CD248KO/KO versus CD248WT/WT mice at the time of sacrifice at Day 23 (Figure 1A), vessel density and pericyte coverage of s.c. T241 fibrosarcomas in CD248WT/WT and CD248KO/KO mice were not significantly different (endothelial-specific CD31 staining, vessels per mm2: 107 ± 18 vessels/mm2 in CD248WT/WT versus 90 ± 8 vessels/mm2 in CD248KO/KO; n = 7, p = 0.40; % vessels covered by smooth muscle actin (SMA)-positive cells: 23.6 ± 5.3 in CD248WT/WT versus 26.7 ± 3.1 in CD248KO/KO; n = 7, p = 0.619).