PECAM1 and neoplasm: To further validate the capability of UCPP to ameliorate tumor hypoxia, HeLa tumor slices striped from the mice 24 h after a single injection of UCPP and laser irradiation were stained with fluorescent dye-labeled antibody to visualize the expression of hypoxia-inducible factor-1α (HIF-1α, green) and CD31 (red), two typical proteins that can indicate the hypoxia level in specific tissues.