PC exosomes were positive for PC initiating cell markers CD44v5, Tspan8, EpCAM, MET and CD104 This effect was not observed for non-malignant PC. miR-1246, miR-4644, miR-3976 and miR-4306 were expressed at higher concentrations in the majority of PC exosomes compared to controls. The gene discussed is ITGB4; the disease is pachyonychia congenita.