PDPN and colorectal cancer: In this study, we used real-time quantitative PCR (RTQ–PCR) to examine the expression of the four kinds of lymphatic endothelial markers in colorectal cancer; meanwhile, we analyzed the difference of expression levels in tumor tissue and para-cancerous tissue and we also analyzed the correlation between the expression levels of LYVE–1, VEGFR–3, Podoplanin, or Prox–1 and lymph node status.