Hepatic CXCL4 levels increase proportionately to fibrotic burden, and CXCL4‐/‐ mice display markedly less hepatic fibrosis in response to injurious stimuli than their wild‐type counterparts.81 Similar findings have been reported in human chronic liver disease; patients with advanced fibrosis have high intrahepatic and serum concentrations of CXCL4.81 A schematic summarizing the platelet role in liver regeneration and fibrosis is shown in Fig. 2. The gene discussed is PF4; the disease is fibrosis.