Su et al (28) revealed that COX-2 and VEGF-C expression in a human tumor cell line showed that VEGF-C was significantly higher in cell lines that overexpress COX-2, and further studies showed that COX-2 may increase VEGF-C expression via EP1 and human epidermal growth factor receptor 2 to promote tumor lymphangiogenesis and lymph node metastasis. This evidence concerns the gene PTGER1 and neoplasm.