# Pathway activation state (phosphosignalling)

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

## TL;DR

Whether a signalling pathway is switched on is set by phosphorylation of its proteins, not by how much of them is present, so it has to be measured at the protein level.

## Summary

Phosphoproteomics identifies and characterises proteins carrying phosphate groups, a reversible modification that regulates protein function, localisation and complex formation (Wikipedia). Kinase pathways such as PI3K/AKT and RAS/MAPK are read from phosphosites (AKT S473, ERK T202/Y204) by mass spectrometry or reverse-phase protein arrays; CPTAC's phosphoproteome and TCGA's RPPA are the public sources. Expression models infer activation indirectly through downstream transcriptional targets such as the SPRY and DUSP genes.

## Fields

- Kind: Term
- Last checked: 2026-09-24
- Also known as: pathway activation state; pathway activation; phosphosignalling; signalling activity; phosphorylation state
- Tags: cansim-terms

## Notes

- Listed in the CanSim terms map 1.0.0 (docs/onco/terms.json, generated 2026-09-24), CC BY 4.0, attribution: CanSim project, an open, public-data-first cancer foundation-model programme; CanSim page path /terms/pathway-activation-state.

## Sources

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

## Connected records

- terms: [Cancer AI vocabulary (CanSim terms map)](https://onco.cc/terms/cancer-ai-vocabulary/), [Deep mass-spectrometry proteome (CPTAC)](https://onco.cc/terms/mass-spec-proteome/), [Gene set enrichment analysis (GSEA and ssGSEA)](https://onco.cc/terms/gsea/), [mRNA to protein concordance](https://onco.cc/terms/mrna-protein-concordance/), [Post-transcriptional and post-translational regulation](https://onco.cc/terms/post-transcriptional-regulation-term/), [Reverse-phase protein array (RPPA)](https://onco.cc/terms/rppa/)
- technologies: [Proteomics & phosphoproteomics](https://onco.cc/technologies/proteomics/)
- pathways: [PI3K / AKT / mTOR](https://onco.cc/pathways/pi3k-akt-mtor/), [RAS / RAF / MEK / ERK (MAPK)](https://onco.cc/pathways/ras-mapk/)
- targets: [PHLPP2](https://onco.cc/targets/phlpp2/), [SPRY4](https://onco.cc/targets/spry4/)

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JSON: https://onco.cc/api/v1/entities/pathway-activation-state.json