Component of the DNA replication complex, which interacts with two kinases, CDK2 and CDC7, thereby providing a functional and physical link between CDK2 and CDC7 during firing of the origins of replication (PubMed:16082200, PubMed:19889979). Regulates ATR-mediated checkpoint signaling in response to DNA damage (PubMed:19889979). Also involved in the cytoplasmic maturation steps of pre-60S ribosomal particles by promoting the release of shuttling protein RSL24D1/RLP24 from the pre-ribosomal particles (PubMed:35354024). Promotes maturation of pre-60S ribosome together with SPATA5, SPATA5L1 and C1orf109 (PubMed:35354024). Homodimer (PubMed:16082200). Interacts with CDK2 and CDC7 (PubMed:16082200). Interacts with the components of the replication complex, MCM2, MCM3, MCM4, MCM5, MCM6, MCM7 and with ORC2-containing complexes (PubMed:16082200). Interacts with ATRIP (PubMed:19889979). Interacts with CEP152 (PubMed:21131973). Associates with pre-60S ribosomal particles (PubMed:35354024). Interacts with C1orf109 (PubMed:35354024). Binds to nuclear under G1 conditions, and dissociates from chromatin with the start of DNA replication. Phosphorylated by CDC7 but not by CDK2. Belongs to the CINP family.