We have investigated the regulation of cell-cycle entry in @entity2199 , taking advantage of its largely invariant and completely described pattern of somatic cell divisions. In a genetic screen, we identified mutations in @entity69823 @entity69824 and @entity69825 @entity69825 . Recent results indicated that during @entity238 development, @entity69824 -dependent kinases regulate cell growth rather than cell division. However, our data indicate that @entity2199 @entity69823 primarily controls G1 progression. To investigate whether @entity69823 and @entity69825 solely act to overcome G1 inhibition by @entity995 family members, we constructed double mutants that completely eliminate the function of the @entity995 family and @entity69824 - @entity69825 kinases. Inactivation of @entity37782 Rb, the single Rb-related gene in @entity2199 , substantially reduced the DNA replication and cell-division defects in @entity69823 and @entity69825 mutant animals. These results demonstrate that @entity37782 Rb is an important negative regulator of G1/S progression and probably a downstream target for @entity69823 and @entity69825 . However, as the suppression by @entity37782 Rb is not complete, @entity69823 and @entity69825 probably have additional targets. An additional level of control over G1 progression is provided by Cip/Kip kinase inhibitors. We demonstrate that @entity37782 Rb and @entity50578 Cip/Kip contribute non-overlapping levels of G1/S inhibition in @entity2199 . Surprisingly, loss of @entity50578 , but not @entity37782 , results in precocious entry into S phase. We suggest that a rate limiting role for @entity50578 Cip/Kip rather than @entity37782 Rb explains the lack of cell-cycle phenotype of @entity37782 mutant animals.

@entity37782 Rb and XXXX Cip/Kip cooperate in developmental regulation of G1 progression in @entity2199 .

@entity2199 :: ('6239', 'Species') :: ['C. elegans'] @entity50578 :: ('174260(Tax:6239)', 'Gene') :: ['cki-1'] @entity69824 :: ('32551(Tax:7227)', 'Gene') :: ['cyclin D'] @entity37782 :: ('172249(Tax:6239)', 'Gene') :: ['lin-35'] @entity69825 :: ('181472(Tax:6239)', 'Gene') :: ['cdk-4', 'Cdk4/6'] @entity69823 :: ('174941(Tax:6239)', 'Gene') :: ['cyd-1'] @entity238 :: ('7227', 'Species') :: ['Drosophila'] @entity995 :: ('MESH:D012175', 'Disease') :: ['retinoblastoma']
@entity50578 :: (174260(Tax:6239),Gene) :: ['cki-1']
