PROX1 and neoplasm: Confocal imaging revealed that 3% of Podoplanin+ tumor lymphatic endothelial cells (TLEC) as well as 3.5% of Prox-1+ or LYVE-1+ TLEC co-expressed GFP, indicating that approximately 3% of tumor-surrounding lymphatic endothelial cells are derived from the bone marrow (Figure 2A).