CXCL12 and neoplasm: Consistent with the proposal that Gr1+CD11b+ cells contribute to tumor angiogenesis, the percentage of endothelial cells (MECA32+) was also decreased following anti-SDF1 treatment (anti-SDF1 group: 4.95 vs. anti-GD group: 10.4; p = 0.009; Fig. 5B).