{"entity":{"id":"mki67","kind":"target","name":"Ki-67 (MKI67)","aka":["Ki67","MIB-1","marker of proliferation Ki-67"],"tldr":"Ki-67 is a protein present only in cells that are dividing, so the share of tumour cells that stain for it is a direct read of how fast the cancer is growing.","summary":"MKI67 encodes a large nuclear protein expressed through the active phases of the cell cycle and absent in resting (G0) cells. The Ki-67 labelling index by immunohistochemistry (antibody MIB-1 on paraffin sections) grades neuroendocrine tumours in the WHO classification and is read in breast cancer as a proliferation marker; the abemaciclib adjuvant approval of 2021 used a Ki-67 score of at least 20 percent as an entry criterion before the label was broadened in 2023. It is a readout, not a drug target: no approved medicine binds Ki-67.","asOf":"2026-09-23","wikipedia":"https://en.wikipedia.org/wiki/Ki-67_(protein)","links":[{"label":"HGNC HGNC:7107","url":"https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:7107"},{"label":"UniProt P46013","url":"https://www.uniprot.org/uniprotkb/P46013/entry"}],"tags":["biomarker-parent"],"related":["ki-67-index"],"cancers":["breast-hr-positive","neuroendocrine"],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["net-grade-ki67","proliferation","ihc"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"MKI67","role":["biomarker"],"evidenceTier":"clinical-evidence","sources":[],"distribution":"few-types","specificityNote":"Specificity not established: no corpus medicine is aimed at it and the catalogues give it only the role biomarker; HPA finds the RNA group enriched, which says where the protein sits but not whether the tumour differs from normal tissue. HPA MKI67: RNA group enriched (bone marrow 44 nTPM, lymphoid tissue 49 nTPM); high antibody staining in 5 normal tissues; highest cancer staining stomach cancer (9 of 12 high). Distribution: 2 cancer families in the corpus carry a prevalence row, label threshold or catalogue link for it (Breast cancer (all types), Neuroendocrine tumours); Open Targets associates it with 0 specific cancer types at or above 0.5. (No rule of scripts/fetch-target-specificity.ts fired.)","specificitySources":[{"label":"Human Protein Atlas MKI67 tissue","url":"https://www.proteinatlas.org/ENSG00000148773-MKI67/tissue","note":"RNA tissue and blood lineage specificity, normal tissue antibody staining (version 25.1, CC BY-SA 3.0)"},{"label":"Open Targets ENSG00000148773 associations","url":"https://platform.opentargets.org/target/ENSG00000148773/associations","note":"cancer associations at or above 0.5 (CC0)"}],"hgnc":"HGNC:7107","ensembl":"ENSG00000148773","uniprot":"P46013","entrez":"4288","firstDescribed":1993,"firstDescribedBasis":"sequence","firstDescribedNote":"Earliest sequence paper UniProt cites for the protein: Schlueter et al, J. Cell Biol, 1993, \"The cell proliferation-associated antigen of antibody Ki-67: a very large, ubiquitous nuclear protein with numerous repeated elements, representing a new kind of cell cycle-maintaining proteins\".","firstDescribedSource":"https://pubmed.ncbi.nlm.nih.gov/8227122/","biology":"Ki-67 coats the surface of mitotic chromosomes and keeps them from clumping; its level rises through S, G2 and M phase and falls to nothing in quiescent cells, which is why the stained fraction tracks proliferation.","whereFound":["Breast cancer (proliferation index)","Neuroendocrine tumours (WHO grade)","Lymphomas and gliomas (proliferation index)"],"targetClass":"other","prevalence":[]},"route":"/targets/mki67/","neighbours":{"biomarker":[{"id":"ki-67-index","kind":"biomarker","name":"Ki-67 index (proliferation by IHC)","route":"/biomarkers/ki-67-index/"}],"cancer":[{"id":"breast-hr-positive","kind":"cancer","name":"HR-positive / HER2-negative breast cancer","route":"/cancers/breast-hr-positive/"},{"id":"neuroendocrine","kind":"cancer","name":"Neuroendocrine tumours","route":"/cancers/neuroendocrine/"}],"term":[{"id":"ihc","kind":"term","name":"Immunohistochemistry (IHC)","route":"/terms/ihc/"},{"id":"net-grade-ki67","kind":"term","name":"Neuroendocrine tumour grade (Ki-67) and WHO classification","route":"/terms/net-grade-ki67/"},{"id":"proliferation","kind":"term","name":"Proliferation","route":"/terms/proliferation/"}],"paper":[{"id":"paper-aparicio-aggressive-variant-prostate-tumour-suppressors-ccr-2016","kind":"paper","name":"Combined tumour suppressor defects characterise clinically defined aggressive variant prostate cancers","route":"/key-papers/paper-aparicio-aggressive-variant-prostate-tumour-suppressors-ccr-2016/"}],"collection":[{"id":"civic","kind":"collection","name":"CIViC","route":"/collections/civic/"}]}}