# Cell cycle

Source: https://onco.cc/terms/cell-cycle/  
OnCo record `cell-cycle` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The ordered sequence a cell goes through to copy its DNA and split in two, with checkpoints along the way where it pauses to check for damage. Cancer cells run through the checkpoints.

## Summary

The phases are G1 (growth), S (DNA copying), G2 (checking) and M (mitosis, the actual division); proteins called cyclins and cyclin-dependent kinases (CDKs) drive the transitions, and tumour suppressors such as RB1 and p53 hold them back until conditions are right. Cancers accelerate the cycle by amplifying cyclin D or losing RB1 and p53, and many drugs act on it: CDK4/6 inhibitors (palbociclib, ribociclib) hold the cell at the G1 checkpoint, while taxanes and vinca alkaloids sabotage mitosis itself. The 'cell-cycle checkpoint' is unrelated to the 'immune checkpoint' of immunotherapy, despite the shared word.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: cell-cycle; cell cycle arrest; cell-cycle arrest; G1 phase; S phase; G2 phase; M phase; mitosis; mitotic

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Cell_cycle
- Wikipedia: https://en.wikipedia.org/wiki/Cell_cycle

## Connected records

- terms: [Cell division](https://onco.cc/terms/cell-division/), [Checkpoint (two meanings)](https://onco.cc/terms/checkpoint/), [Chemotherapy](https://onco.cc/terms/chemotherapy-term/), [Kinase](https://onco.cc/terms/kinase/), [Proliferation](https://onco.cc/terms/proliferation/), [Tumour suppressor gene](https://onco.cc/terms/tumour-suppressor-gene/)
- technologies: [CDK4/6 inhibitors](https://onco.cc/technologies/cdk46-inhibitor/)
- targets: [CDK4/6](https://onco.cc/targets/cdk4-6/), [TP53](https://onco.cc/targets/tp53/), [WEE1](https://onco.cc/targets/wee1/)
- drugs: [Abemaciclib](https://onco.cc/drugs/abemaciclib/), [Paclitaxel / nab-paclitaxel](https://onco.cc/drugs/paclitaxel/), [Palbociclib](https://onco.cc/drugs/palbociclib/), [Ribociclib](https://onco.cc/drugs/ribociclib/)
- pathways: [p53 / RB / cell-cycle checkpoint](https://onco.cc/pathways/p53-cell-cycle/)
- key papers: [Comprehensive genomic profiles of small cell lung cancer](https://onco.cc/key-papers/paper-george-sclc-genomic-profiles-nature-2015/), [El-Deiry 1993: WAF1, the gene through which p53 stops cell division](https://onco.cc/key-papers/paper-el-deiry-waf1-p21-cell-1993/), [Levine 1997: p53, the cellular gatekeeper for growth and division](https://onco.cc/key-papers/paper-levine-p53-gatekeeper-cell-1997/), [Sherr and Roberts 1999: CDK inhibitors as regulators of the G1 phase](https://onco.cc/key-papers/paper-sherr-roberts-cdk-inhibitors-genesdev-1999/)

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