Cell cycle G1-S transition pathway

The G1 to S-phase transition of the cell cycle is tightly controlled. This pathway card outlines the mechanisms through which cyclins and cyclin-dependent kinases (Cdks) regulate cell cycle progression at the G1 to S-phase transition.

At the G1 to S-phase transition various stimuli such as DNA damage or growth factor withdrawal can result in a stop in cell cycle progression through regulation of Cyclin D–Cdk4/6 or Cyclin E–Cdk2 complex activity and the Retinoblastoma protein Rb. Entry into S-phase is controlled by Rb that sequesters the E2F family of transcription factors away from their target genes, expression of which is required for entry into S-phase.