We have also observed an association of ET-1 expression with time to PSA recurrence, in accordance with results from Rosenblatt et al. [12] who demonstrated that both the intensity and the combination product of intensity and extent of ET-1 immunoreactivity (IRp) but not the staining extent alone predicted biochemical relapse in a large-scale study of 287 PC specimens from RP. Here, EDN1 is linked to pachyonychia congenita.