Although Yoshida et al. demonstrated that calpeptin can reduce the expression of CAPN2 and suppress the tumor progression of PC in a mouse xenograft model (18), to explore the possible functional significance of CAPN2 in PC cells, we knocked down CAPN2 via siRNA in Panc-1 and SW1990 cells. This evidence concerns the gene CAPN2 and pachyonychia congenita.