CCNA2 and oculopharyngeal muscular dystrophy: Mortal OPMD keratinocytes had much higher ratios of cyclin D1/cyclin A, cyclin D1/cyclin E1, and cylinD1/Cdk1 relative to the normal and immortal OPMD keratinocytes, findings that are consistent with a reduced passage through the restriction point and entry into S phase [58,138].