PGF and neoplasm: Correlation analysis displayed existing moderate VEGF/VEGFR-1 and weak PlGF/VEGFR-1 ligand-receptor affinity (r = 0.5, p = 0.0001 as well as r = 0.3, p = 0.007 in tumor center and r = 0.3 and p = 0.02 in tumor budding, respectively; Table 2).