| Name: | Mouse monoclonal antibody to human Ki67 |
| Immunogen: | Recombinant construct containing the N-terminal 300 amino acids of the human sequence expressed in and purified from E. coli. |
| HGNC Name: | MKI67 |
| UniProt: | P46013 |
| Molecular Weight: | 345kDa, 395kDa |
| Host: | Mouse |
| Isotype: | IgG1 |
| Species Cross-Reactivity: | Human, not rodent |
| RRID: | AB_2637052 |
| Format: | Purified antibody at 1mg/mL in 50% PBS, 50% glycerol, 5mM azide |
| Applications: | WB, IF/ICC |
| Recommended Dilutions: | WB: 1:1,000-5,000. IF 1:2,000-5,000 |
| Storage: | Store at 4°C for short term. For longer term, store at -20°C |
Immunofluorescent analysis of HeLa cells stained with mouse mAb to Ki67, MCA-6G3, dilution 1:2,000 (red). The blue is DAPI staining of nuclear DNA. The MCA-6G3 antibody stains Ki67 protein predominantly expressed in the nucleoli of rapidly dividing cells, while nearby quiescent cells express little or no Ki67. The Ki67 protein also coats the surface of condensed chromosomes as seen at the middle left of the image.
Western blot analysis of equal amounts of cell lysates using mouse mAb to Ki67, MCA-6G3, dilution 1:2,000, in green: [1] protein standard (red), [2] rapidly dividing HeLa cell cultures, [3] rapidly dividing HEK293 cell cultures. Strong double bands above 250kDa correspond to the two major Ki67 isoforms of apparent molecular weight of 345 and 395kDa. Smaller proteolytic fragments of these isoforms are also invariably detected on the blot.
Mouse Monoclonal Antibody to Human Ki67, Ki-67
Cat# MCA-6G3
$120.00 – $800.00
The Ki67 proteins were first discovered in an attempt to generate cancer specific monoclonal antibodies (1). A monoclonal antibody which bound to structures in the nuclei of dividing but not quiescent cells was produced and shown to bind two very large proteins of molecular weight 345kDa and 395kDa. The two proteins were derived from alternate transcripts of a single gene. The presence of Ki67 proteins, detected with an appropriate antibody, is an indicator of cell proliferation and the level of Ki67 expression is one of the most reliable biomarkers of proliferative status of cancer cells (2-7). Recent studies show that Ki67 coats dividing chromosomes and ensures that each one enters the appropriate daughter cell (8). The MCA-6G3 monoclonal antibody was raised against a recombinant construct containing the N-terminal 300 amino acids of human Ki67 isotype 1, as laid out in the Uniprot entry P46013. The Ki67 protein sequence is quite variable across species boundaries, and therefore antibody to the human protein often fails to recognize the rodent homologue and vice versa. As a result this antibody is not recommended for studies of rodents. Mouse select image at left for larger view.
The Ki67 protein was first discovered in an attempt to generate cancer specific monoclonal antibodies. Mice were injected with nuclear preparations from Hodgkin’s lymphoma cells. One hybridoma produced an antibody which strongly stained the nucleoli of dividing but not quiescent cells. The antibody was named Ki67; the name was derived of Kiel, Germany which was where the work was performed, and the number 67 was the well number in which hybridoma was first identified (1). The original Ki67 antibody recognizes a very large protein with two isoforms of 345kDa and 395kDa. Western blots often show a ladder of smaller fragments of these isoforms since the proteins are rather unstable, consistent with their short in vivo half-life of about 1 hour. The two Ki67 proteins were found to be heavily expressed in proliferating cells, but to be absent in quiescent cells (2). The presence of the Ki67 protein is frequently used as an indicator of cell proliferation and its level of expression is one of the most reliable biomarkers of proliferative status of cancer cells. Much research shows a correlation between Ki67 protein level and prognosis in cancer patients, when high Ki67 levels being associated with poorer outcomes (3-7). The original Ki67 antibody and several others have become so widely used that a search for “(ki-67 or Ki67) AND antibody” in PubMed in August 2018 produced over 5,600 results. Recent studies show that Ki67 functions as a “biological surfactant”, which is essential for the separation of condensed chromosomal DNA into the two daughter cells during cell division (8). This presumably explains the highly basic nature of Ki67, allowing a charge-based interaction with nucleic acids, and the lack of this protein in non-dividing cells.
This mouse monoclonal antibody was raised against a recombinant construct containing the N-terminal 300 amino acids of human Ki67 isotype 1, as laid out in the Uniprot entry P46013. The Ki67 protein sequence is quite variable across species barriers, and therefore antibodies to the human protein often fail to recognize the rodent homologue and vice versa. This antibody works well on human material but is not recommended for studies of rodent cells or tissues.
1. Gerdes J, Schwab U, Lemke H, Stein H. Production of a mouse monoclonal antibody reactive with a human nuclear antigen associated with cell proliferation. Int. J. Cancer 31:13-20 (1983).
2. Kill IR, Faragher RGA, Lawrence K. Shall S. The expression of proliferation-dependent antigens during the lifespan of normal and progeroid human fibroblasts in culture. J. Cell Sci. 107:571-9 (1994).
3. Yerushalmi R, et al. Ki67 in breast cancer: Prognostic and predictive potential. Lancet Oncol. 11:174–83 (2010).
4. Josefsson A, et al. Low endoglin vascular density and Ki67 index in Gleason score 6 tumours may identify prostate cancer patients suitable for surveillance. Scand. J. Urol. Nephrol. 46:247–57 (2012).
5. Ishihara M, et al. Retrospective analysis of risk factors for central nervous system metastases in operable breast cancer: effects of biologic subtype and Ki67 overexpression on survival. Oncology. 84:135–140 (2013).
6. Cheang MC, et al. Ki67 Index, HER2 Status, and Prognosis of Patients With Luminal B Breast Cancer. J. Natl. Cancer Inst. 101:736-50 (2009).
7. Margulis V, et al. Multi-institutional validation of the predictive value of Ki-67 labeling index in patients with urinary bladder cancer. J. Natl. Cancer Inst. 101:114-9 (2009).
8. Cuylen S, et al. Ki-67 acts as a biological surfactant to disperse mitotic chromosomes.Nature. 535:308-12 (2016).
