ERCC6 and xeroderma pigmentosum: At least eight core genes (i.e., ERCC1, XPA, XPB/ERCC3, XPC, XPD/ERCC2, XPE, XPF/ERCC4, and XPG/ERCC5) derived from the xeroderma pigmentosm (XP) complementation group, together with other two genes (i.e., CSA /ERCC8 and CSB/ERCC6) encoding proteins linked to Cockayne's syndrome, are involved in the pathway [2, 3], among which the XP genes were extensively investigated in the development of cancer, both in vivo and in vitro.