Negative cell-cycle regulator that functions at the G1-to-S-phase transition (PubMed:10587644, PubMed:9716524). Required for suspension of the cell cycle in dauer larvae and starved L1 larvae (PubMed:10587644, PubMed:9716524). In vulval precursor cells (VPCs), a pathway of heterochronic genes acts via cki-1 to maintain VPCs in G1 during the L2 larval stage (PubMed:10587644, PubMed:9716524, PubMed:15247923). Cul-2 may function in ubiquitin-mediated degradation by targeting cki-1 for degradation (PubMed:10587644). Involved in distal tip cell development by repressing and modulating cye-1/cdk-2 activity levels in Z1.aa/Z4.pp and in Z1.ap/Z4.pa (PubMed:17476329). Interacts with cyd-1 (Probable); the interaction is direct. In embryos, expression is first seen in pharyngeal primordium and later in all differentiating cells. Post embryonic expression corresponds to developmental patterns of cell cycle progression in many tissues including sex myoblasts, distal tip cells, vulval cells, seam cells, neurons, intestine cells and hypodermal cells. In embryos, expression is first seen in pharyngeal primordium and later in all differentiating cells. Post embryonic expression corresponds to developmental patterns of cell cycle progression in many tissues including sex myoblasts, distal tip cells, vulval cells, seam cells, neurons, intestine cells and hypodermal cells (PubMed:10587644, PubMed:9716524). During the development of distal tip cells (DTC), expressed asymmetrically between the daughters of the Z1.a and Z4.p cells; asymmetric expression is regulated by wrm-1, a component of the Wnt/MAPK pathway (PubMed:17476329). RNAi-mediated knockdown results in additional cell divisions in postembryonic intestinal cells characterized by a premature entry into S phase. Belongs to the CDI family.