FLT4 and angiosarcoma: In addition to high expression levels of the proliferative proteins Ki67 and cyclins A, D and E [22], angiosarcomas show remarkably variable expression in key angiogenic regulators such as VEGF-A (0–94% of angiosarcomas), VEGF-B (39% of angiosarcomas, though only tested in one report), VEGF-C (12–100% of angiosarcomas), VEGF-D (100% of angiosarcomas, though only tested in one report), VEGFR1 (62–79% of angiosarcomas), VEGFR2 (64–94% of angiosarcomas), and VEGFR3 (79–100% of angiosarcomas) [22–29].