# MED23

Source: https://onco.cc/targets/med23/  
OnCo record `med23` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

MED23 (Mediator of RNA polymerase II transcription subunit 23) is a gene whose normal job is to hold cell growth in check. The public catalogues list it as a tumour suppressor, and it is called a cancer driver by mutation analysis of patient cohorts. Tied to Breast cancer.

## Summary

Required for transcriptional activation subsequent to the assembly of the pre-initiation complex. Component of the Mediator complex, a coactivator involved in the regulated transcription of nearly all RNA polymerase II-dependent genes. Mediator functions as a bridge to convey information from gene-specific regulatory proteins to the basal RNA polymerase II transcription machinery.

IntOGen calls it a driver in 1 cohort (0 activating, 1 loss-of-function), covering Invasive Breast Carcinoma.

## Fields

- Kind: Target
- Last checked: 2026-09-23
- Also known as: mediator complex subunit 23; Mediator of RNA polymerase II transcription subunit 23; CRSP130; DRIP130; Sur2; CRSP3; MRT18
- Tags: cancer-genes-wave
- Symbol: MED23
- Class: tumor-suppressor
- Biology: Required for transcriptional activation subsequent to the assembly of the pre-initiation complex. Component of the Mediator complex, a coactivator involved in the regulated transcription of nearly all RNA polymerase II-dependent genes. Mediator functions as a bridge to convey information from gene-specific regulatory proteins to the basal RNA polymerase II transcription machinery. Mediator is recruited to promoters by direct interactions with regulatory proteins and serves as a scaffold for the assembly of a functional pre-initiation complex with RNA polymerase II and the general transcription factors. Required for transcriptional activation by adenovirus E1A protein. Required for ELK1-dependent transcriptional activation in response to activated Ras signalling. Location: Nucleus (UniProt). Locus 6q23.2 (HGNC).
- Where found: Breast cancer: IntOGen driver in 1 cohort (BRCA)

## 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: IntOGen calls it a loss-of-function (LoF) driver in 1 cohort. Evidence tier "cohort-driver" is the strongest of those signals.
- Prevalence not recorded: none of the sources gives a positivity rate.

## Sources

- HGNC HGNC:2372: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:2372
- UniProt Q9ULK4: https://www.uniprot.org/uniprotkb/Q9ULK4/entry
- NCBI Gene 9439: https://www.ncbi.nlm.nih.gov/gene/9439
- Ensembl ENSG00000112282: https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000112282

## Connected records

- collections: [IntOGen](https://onco.cc/collections/intogen/)
- cancers: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/)

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JSON: https://onco.cc/api/v1/entities/med23.json