# JAK1

Source: https://onco.cc/targets/jak1/  
OnCo record `jak1` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

JAK1 is one of the kinases that pass cytokine and interferon signals inside immune and blood cells. Ruxolitinib and momelotinib block JAK1 together with JAK2 to calm the inflammation of myelofibrosis; golidocitinib is the first JAK1-only inhibitor approved for a cancer, in peripheral T-cell lymphoma.

## Summary

JAK1 (chromosome 1p31.3) is a non-receptor tyrosine kinase that phosphorylates the signal-transducing subunits of cytokine receptor complexes including IL2RB, IL10RA, IFNAR2, IL6ST, LIFR, OSMR and IL31RA; it is required for interferon alpha, beta and gamma signalling, where it phosphorylates IFNAR2 to create STAT docking sites, and it activates STATs directly or through partner JAK kinases (UniProt P23458). In OnCo, JAK1 is inhibited with JAK2 by ruxolitinib and momelotinib for spleen and symptom control in myelofibrosis, deliberately spared by pacritinib to limit myelosuppression, and selectively targeted by golidocitinib, approved in China in 2024 for relapsed peripheral T-cell lymphoma.

## Fields

- Kind: Target
- Last checked: 2026-09-22
- Also known as: Janus kinase 1; JAK1A; JTK3
- Tags: wave5-target
- Symbol: JAK1
- Class: kinase
- Biology: The JAK-STAT pathway record notes that interferon-gamma signalling through JAK1/2 and STAT1 raises MHC and PD-L1 expression, and that JAK1/2 loss-of-function mutations cause acquired resistance to PD-1 blockade, so JAK1 is both a drug target in blood cancers and a resistance gene in immunotherapy.
- Where found: Myelofibrosis and other myeloproliferative neoplasms (JAK1/2 inhibitors); Peripheral T-cell lymphoma (golidocitinib); Tumours with JAK1 loss (checkpoint resistance)

## Notes

- Prevalence not recorded in this wave: HGNC and UniProt carry no positivity rates and no other source was consulted.

## Sources

- HGNC HGNC:6190: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:6190
- UniProt P23458: https://www.uniprot.org/uniprotkb/P23458/entry
- NCBI Gene 3716: https://www.ncbi.nlm.nih.gov/gene/3716

## Connected records

- drugs: [Golidocitinib](https://onco.cc/drugs/golidocitinib/), [Momelotinib](https://onco.cc/drugs/momelotinib/), [Pacritinib](https://onco.cc/drugs/pacritinib/), [Ruxolitinib](https://onco.cc/drugs/ruxolitinib/)
- targets: [JAK2](https://onco.cc/targets/jak2/)
- cancers: [Myeloproliferative neoplasms (PV, ET, myelofibrosis)](https://onco.cc/cancers/myeloproliferative-neoplasms/), [Peripheral T-cell lymphomas (including cutaneous T-cell lymphoma)](https://onco.cc/cancers/peripheral-t-cell-lymphoma/), [Primary myelofibrosis](https://onco.cc/cancers/primary-myelofibrosis/)
- technologies: [Small-molecule kinase inhibitors](https://onco.cc/technologies/kinase-inhibitors/)
- pathways: [Antigen presentation & immune editing](https://onco.cc/pathways/antigen-presentation-immunoediting/), [JAK-STAT signalling](https://onco.cc/pathways/jak-stat/)

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JSON: https://onco.cc/api/v1/entities/jak1.json