Marker of proliferation Ki-67 protein (Ki-67)

The marker of proliferation Ki-67 protein is a large, predominantly unstructured nuclear protein encoded by the MKI67 gene in humans[6][7][4][5]. It contains characteristic domains, including a forkhead-associated (FHA) domain, a PP1-binding domain, and a highly repetitive region unique to the protein, as well as a chromatin-binding C-terminal region[4][5][2]. Ki-67 is present during all active phases of the cell cycle (G1, S, G2, and M phases) but absent in quiescent cells (G0), making it a robust indicator of cell proliferation[2][3][6]. Although historically thought to be required for proliferation, genetic studies reveal Ki-67 is not essential for cell division but rather plays roles in nucleolar structure, perichromosomal layer formation, and possibly liquid–liquid phase separation[1][2][5]. Due to its strong correlation with cellular proliferation, Ki-67 is widely used in oncology as a diagnostic, prognostic, and grading marker, with high expression correlating with tumor aggressiveness[3][6]. There are no known drugs that directly target Ki-67, and it is not considered a therapeutic target but rather a valuable biomarker[3].

Other names

Ki-67MKI67Antigen Kiel 67Proliferation marker protein Ki-67pKi67