CHEK1 and pachyonychia congenita: In this study, we reached the following conclusions: (1) NCAPH was upregulated in PC tissues and cell lines; (2) knockdown of NCAPH induced cell cycle arrest and cell apoptosis; (3) NCAPH was important for proper progression of MCC from poorly condensed chromosomes; and (4) NCAPH knockdown induced DNA damage though the Chk1/Chk2 signaling pathway.