PECAM1 and neoplasm: Paraffin-embedded RF420 lung metastases underwent IHC with a CD31 antibody, and microvascular density counts/HPF were 64.0 ± 5.04 in the control group and reduced to 41.4 ± 6.29 in hSFRP2 mAb-treated group (n = 10, p < 0.001, Figure 1C), demonstrating that hSFRP2 mAb inhibits tumor angiogenesis in a GEMM model.