# MPS1 (TTK)

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

## TL;DR

MPS1 arms the checkpoint that holds a dividing cell until its chromosomes are attached. Blocking it lets cancer cells divide carelessly and die; one inhibitor is in phase 1/2 in breast cancer.

## Summary

TTK (chromosome 6q14.1) encodes the dual-specificity kinase MPS1, which is involved in mitotic spindle assembly checkpoint signalling, delaying anaphase until chromosomes are bioriented, and in the repair of incorrect kinetochore-microtubule attachments; it phosphorylates MAD1L1 to promote the checkpoint and is present in rapidly proliferating cell lines (UniProt P33981). CFI-402257, a TTK inhibitor, is in phase 1/2 alone, with fulvestrant, and with paclitaxel in HER2-negative breast cancer (NCT05251714, NCT03568422).

## Fields

- Kind: Target
- Last checked: 2026-09-24
- Also known as: MPS1; Mps1; TTK protein kinase; PYT; CT96
- Tags: checkpoint-map
- Symbol: TTK
- Class: kinase
- Biology: The apex kinase of the spindle assembly checkpoint; inhibitors override the checkpoint rather than enforce it.
- Where found: Rapidly proliferating cells (UniProt P33981); Breast cancer trials of CFI-402257

## Notes

- Prevalence not recorded: HGNC and UniProt carry no positivity rates.

## Sources

- HGNC HGNC:12401: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:12401
- UniProt P33981: https://www.uniprot.org/uniprotkb/P33981/entry
- NCBI Gene 7272: https://www.ncbi.nlm.nih.gov/gene/7272
- ClinicalTrials.gov NCT05251714: https://clinicaltrials.gov/study/NCT05251714

## Connected records

- targets: [AURKA](https://onco.cc/targets/aurka/), [AURKB](https://onco.cc/targets/aurkb/), [BUB1](https://onco.cc/targets/bub1/)
- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/)
- pathways: [Mitosis & the spindle assembly checkpoint](https://onco.cc/pathways/mitotic-spindle-checkpoint/)
- terms: [Checkpoint (two meanings)](https://onco.cc/terms/checkpoint/)

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JSON: https://onco.cc/api/v1/entities/ttk.json