The retinoblastoma gene product regulates progression through the G1 phase of the cell cycle

Cell. 1991 Oct 18;67(2):293-302. doi: 10.1016/0092-8674(91)90181-w.


The RB gene product is a nuclear phosphoprotein that undergoes cell cycle-dependent changes in its phosphorylation status. To test whether RB regulates cell cycle progression, purified RB proteins, either full-length or a truncated form containing the T antigen-binding region, were injected into cells. Injection of either protein early in G1 inhibits progression into S phase. Co-injection of anti-RB antibodies antagonizes this effect. Injection of RB into cells arrested at G1/S or late in G1 has no effect on BrdU incorporation, suggesting that RB does not inhibit DNA synthesis in S phase. These results indicate that RB regulates cell proliferation by restricting cell cycle progression at a specific point in G1 and establish a biological assay for RB activity. Neither co-injection of RB with a T antigen peptide nor injection into cells expressing T antigen prevents cells from progressing into S phase, which supports the hypothesis that T antigen binding has functional consequences for RB.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antigens, Viral / physiology
  • Aphidicolin / pharmacology
  • Baculoviridae / genetics
  • Bromodeoxyuridine / pharmacology
  • Cell Line
  • Electrophoresis, Polyacrylamide Gel
  • Escherichia coli / metabolism
  • G1 Phase / drug effects*
  • Humans
  • Hydroxyurea / pharmacology
  • Insecta
  • Microinjections
  • Microscopy, Fluorescence
  • Nocodazole / pharmacology
  • Osteosarcoma
  • Phosphorylation
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / pharmacology
  • Retinoblastoma Protein / pharmacology*
  • Simian virus 40 / genetics
  • Tumor Cells, Cultured


  • Antigens, Viral
  • Recombinant Proteins
  • Retinoblastoma Protein
  • Aphidicolin
  • Bromodeoxyuridine
  • Nocodazole
  • Hydroxyurea