text: pRb restricts the cells ability to replicate DNA by preventing its progression from the G1 (first gap phase) to S (synthesis phase) phase of the cell division cycle. pRb binds and inhibits E2 promoter-binding–protein-dimerization partner (E2F-DP) dimers, which are transcription factors of the E2F family that push the cell into S phase. By keeping E2F-DP inactivated, RB1' maintains the cell in the G1 phase, preventing progression through the cell cycle and acting as a growth suppressor.  The pRb-E2F/DP complex also attracts a histone deacetylase (HDAC) protein to the chromatin, reducing transcription of S phase promoting factors, further suppressing DNA synthesis.