MKI67 and pachyonychia congenita: In order to know whether the impairment in the growth of neurospheres observed in PC NPCs treated with TAT-Cx43266–283 was due to a decrease in cell proliferation, to an increase in cell death, or to both mechanisms, we evaluated cell proliferation and apoptosis in PC NPCs by Ki67 and caspase-3 immunostaining, respectively.