SPI1 and neoplasm: While these reports support the pro-lymphatic role of VEGFR-3, this concept does not explain well-established observations associated with lymphatic sprouting: (1) expression of LEC-specific markers VEGFR-3 [14], LYVE-1 [15], and podoplanin [16] in tumor-associated macrophages (TAMs); and (2) expression of myeloid markers CD11b [14], CD68 [17], or PU.1 [17] in tumor but not normal lymphatic vessels.