CASP3 and pachyonychia congenita: Consistent with these findings, an immunohistochemical analysis for the proliferation (Ki67) and the apoptosis (cleaved caspase 3) indicated that inhibition of SQLE markedly decreased cell proliferation and augmented apoptosis in PC xenografts, whereas SQLE overexpression showed the opposite results (Fig. 3G, H and Supplementary Fig. S2G, H).