C. elegans MCM-4 is a general DNA replication and checkpoint component with an epidermis-specific requirement for growth and viability

► lin-6 mutants are defective in DNA synthesis but continue mitosis during postembryonic development. ► The lin-6 gene encodes the C. elegans homologue of the MCM-4 subunit of the MCM2-7 replicative helicase complex. ► lin-6/mcm-4 is required for checkpoint function when DNA replication is incomplete. ► lin-6/mcm-4 is specifically required in the epidermis for postembryonic growth and viability.