Ki67/MKI67 Antibodies & Proteins — Proliferation Marker

If you work in oncology, you've probably counted Ki67-positive cells at least once. Encoded by the MKI67 gene, Ki67 is expressed during every active phase of the cell cycle — G1, S, G2, and M — but disappears completely when cells enter quiescence (G0). That on/off switch makes it the single most reliable marker for cell proliferation, and the reason it has become one of the most widely studied biomarkers in cancer research.

abinScience offers anti-Ki67/MKI67 polyclonal antibodies (human and mouse) and recombinant Ki67 proteins, all affinity-purified and validated for WB, IHC, and ELISA.

Ki67 as a Proliferation Biomarker in Cancer Research

The Ki67 labeling index — the percentage of Ki67-positive nuclei in a tissue section — is one of the most studied readouts in translational oncology. In breast cancer research, Ki67 has been extensively investigated as a biomarker for stratifying tumor subtypes and predicting response to therapy, which has driven decades of research into standardized scoring methods and inter-laboratory reproducibility.

Ki67 staining is also widely used in preclinical and translational studies of neuroendocrine tumors, lymphomas, and gliomas. In the research setting, Ki67 immunostaining remains the standard method for quantifying tumor growth rates in xenograft models, evaluating anti-proliferative drug efficacy, and assessing the proliferative fraction in primary cell cultures.

Available Products

Anti-Ki67/MKI67 Antibodies

Ki67/MKI67 Recombinant Proteins

Practical Notes for Ki67 Detection

The following are suggested starting conditions. Optimal dilutions and protocols should be determined by the end user for each specific application and sample type.

How Ki67 Works: Chromosome Surfactant

For decades, Ki67 was treated as a black-box marker — everyone knew it labeled proliferating cells, but nobody knew why. That changed in 2016, when Cuylen et al. showed that Ki67 functions as a biological surfactant on mitotic chromosomes.

During early mitosis, Ki67 relocates from nucleoli to the chromosome surface, where it forms extended brush structures. These brushes carry a high net negative charge that creates a steric and electrostatic barrier between individual chromosomes — preventing them from collapsing into a single clump after the nuclear envelope breaks down. In anaphase, the brush collapses and Ki67 switches from repellent to attractant, pulling chromosomes together to rebuild the nucleus and exclude cytoplasmic components from the nuclear space.

This mechanism explains two things researchers have long taken for granted: why Ki67 is universally present in every dividing cell regardless of tissue type (it is required for proper chromosome segregation), and why it disappears in G0 (quiescent cells do not need chromosome separation machinery).

Gene: MKI67  |  UniProt: P46013 (Human), E9PVX6 (Mouse)  |  Also known as: Ki-67, Antigen KI-67, Proliferation marker protein Ki-67

For research use only. Not intended for diagnostic or therapeutic use.