PF4 and Hermansky-Pudlak syndrome: We have previously proved that angiogenic growth factors, such as VEGF (especially VEGF-C), bFGF, IL-8, and MMP-9 [17,20,24,33], as well as anti-angiogenic factors such as TSP-1 and PF-4 [17,20,24,31], are strongly upregulated in HPS in comparison to unstimulated serum.