# BLK

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

## TL;DR

BLK (Tyrosine-protein kinase Blk) is a protein kinase, an enzyme that switches other proteins on by adding phosphate groups. The public catalogues list it as a drug target and a biomarker, and an approved or late-stage drug is recorded against it. Tied to Leukaemia, Myeloproliferative neoplasms, Non-Hodgkin lymphoma and 2 more.

## Summary

Non-receptor tyrosine kinase involved in B-lymphocyte development, differentiation and signalling. B-cell receptor (BCR) signalling requires a tight regulation of several protein tyrosine kinases and phosphatases, and associated coreceptors. Binding of antigen to the B-cell antigen receptor (BCR) triggers signalling that ultimately leads to B-cell activation.

CIViC holds 1 clinical evidence item and 0 assertions across 1 variant, naming Ibrutinib. Open Targets scores its association with cancer at 0.68 (direct and indirect evidence; datatypes literature 0.81, genetic association 0.48, clinical 0.96).

## Fields

- Kind: Target
- Last checked: 2026-09-23
- Also known as: BLK proto-oncogene, Src family tyrosine kinase; Tyrosine-protein kinase Blk; MGC10442
- Tags: cancer-genes-wave
- Symbol: BLK
- Class: kinase
- Biology: Non-receptor tyrosine kinase involved in B-lymphocyte development, differentiation and signalling. B-cell receptor (BCR) signalling requires a tight regulation of several protein tyrosine kinases and phosphatases, and associated coreceptors. Binding of antigen to the B-cell antigen receptor (BCR) triggers signalling that ultimately leads to B-cell activation. Signalling through BLK plays an important role in transmitting signals through surface immunoglobulins and supports the pro-B to pre-B transition, as well as the signalling for growth arrest and apoptosis downstream of B-cell receptor. Specifically binds and phosphorylates CD79A at 'Tyr-188'and 'Tyr-199', as well as CD79B at 'Tyr-196' and 'Tyr-207'. Also phosphorylates the immunoglobulin G receptors FCGR2A, FCGR2B and FCGR2C. Location: Cell membrane (UniProt). Locus 8p23.1 (HGNC).
- Where found: Leukaemia: Open Targets association 0.61 with leukaemia (MONDO_0005059); Myeloproliferative neoplasms: Open Targets association 0.60 with myeloproliferative neoplasm (MONDO_0020076); Non-Hodgkin lymphoma: Open Targets association 0.56 with non-Hodgkin lymphoma (MONDO_0018908); Chronic myeloid leukaemia: Open Targets association 0.60 with chronic myelogenous leukaemia, BCR-ABL1 positive (MONDO_0011996); Acute lymphoblastic leukaemia: Open Targets association 0.55 with acute lymphoblastic leukaemia (MONDO_0004967)

## Notes

- Written by scripts/fetch-cancer-genes.ts from CIViC, Open Targets, IntOGen, HGNC and UniProt; the function text is UniProt's, condensed and in UK spelling. Roles: Open Targets known-drug datatype score 0.97; CIViC holds 1 clinical evidence items on its variants. Evidence tier "approved-drug" is the strongest of those signals.
- Prevalence not recorded: none of the sources gives a positivity rate.
- Diseases the sources name that have no OnCo cancer page yet, so they are not linked: B-cell Acute Lymphoblastic Leukaemia.

## Sources

- HGNC HGNC:1057: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:1057
- UniProt P51451: https://www.uniprot.org/uniprotkb/P51451/entry
- NCBI Gene 640: https://www.ncbi.nlm.nih.gov/gene/640
- Ensembl ENSG00000136573: https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000136573

## Connected records

- collections: [CIViC](https://onco.cc/collections/civic/), [Open Targets Platform](https://onco.cc/collections/open-targets/)
- cancers: [Acute lymphoblastic leukaemia](https://onco.cc/cancers/all-leukemia/), [Chronic myeloid leukaemia (CML)](https://onco.cc/cancers/cml/), [Leukaemia (all types)](https://onco.cc/cancers/leukaemia/), [Myeloproliferative neoplasms (PV, ET, myelofibrosis)](https://onco.cc/cancers/myeloproliferative-neoplasms/), [Non-Hodgkin lymphoma (all types)](https://onco.cc/cancers/non-hodgkin-lymphoma/)

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