PROX1 and neoplasm: To trace the fate of cells of the myeloid lineage during tumor lymphangiogenesis, Zumsteg et al. [89] transplanted TRAMP-C1 murine prostate cancer cells into CD11b-Cre; Z/EG mice and subsequently detected the LYVE-1, Prox-1, and F4/80 triple-positive cells in tumor lymphatic vessels, testifying an already myeloid-committed hematopoietic lineage origin.