Although there have been a limited number of reports describing exosomal miRNA as a marker for PC [49], we and others have reported exosomal protein markers that would be helpful to diagnose PC (PSMA), taxane-resistant CRPC (P-gp) and progression and aggressiveness of PC (integrin β4 and vinculin) [12–16]. The gene discussed is VCL; the disease is pachyonychia congenita.