title: Cell cycle-dependent regulation of phosphorylation of the human retinoblastoma gene product.
abstract: The human retinoblastoma gene (RB1) encodes a protein (Rb) of 105 kilodaltons that can be phosphorylated. Analysis of Rb metabolism has shown that the protein has a half-life of more than 10 hours and is synthesized at all phases of the cell cycle. Newly synthesized Rb is not extensively phosphorylated (it is "underphosphorylated") in cells in the G0 and G1 phases but is phosphorylated at multiple sites at the G1/S boundary and in S phase. HL-60 cells that were induced to terminally differentiate by various chemicals lost their ability to phosphorylate newly synthesized Rb at multiple sites when cell growth was arrested. These findings suggest that underphosphorylated Rb may restrict cell proliferation.
authors.affiliation: Division of Hematology/Oncology and Ophthalmology, Childrens Hospital of Los Angeles, CA.
authors.forename: K
authors.initials: K
authors.lastname: Mihara
authors.forename: X R
authors.initials: XR
authors.lastname: Cao
authors.forename: A
authors.initials: A
authors.lastname: Yen
authors.forename: S
authors.initials: S
authors.lastname: Chandler
authors.forename: B
authors.initials: B
authors.lastname: Driscoll
authors.forename: A L
authors.initials: AL
authors.lastname: Murphree
authors.forename: A
authors.initials: A
authors.lastname: T'Ang
authors.forename: Y K
authors.initials: YK
authors.lastname: Fung
mesh_terms: D002453:Cell Cycle / Q000235:genetics*; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D005134:Eye Neoplasms / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007399:Interphase / Q000235:genetics; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000235:genetics*; D012175:Retinoblastoma / Q000235:genetics*; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D009363:Neoplasm Proteins; D014212:Tretinoin