Future studies will be needed to decipher the exact causes and mechanisms that lead to decreased amounts of intracellular PF4/CXCL4 cargo in platelets from PV patients; this could include not only platelet responses to IEs but also responses to other stimuli within the vasculature, and changes at the level of platelet production by megakaryocytes [39]. Here, PF4 is linked to acquired polycythemia vera.