Proliferation marker protein Ki-67 (Ki-67)

Proliferation marker protein Ki-67 is a large, nuclear protein encoded by the MKI67 gene and is strictly expressed in actively proliferating cells but absent in quiescent cells. This characteristic makes Ki-67 the gold-standard proliferation marker in clinical cancer diagnostics and research, where its expression is measured as the "Ki-67 index" to help assess tumor growth fraction, inform prognosis, and guide therapy decisions, especially in breast and other cancers. The protein is not an enzyme, receptor, or therapeutic target, but functions in organizing perichromosomal material during mitosis, regulating heterochromatin structure, and influencing gene expression. Despite its association with proliferative activity and its use as a tumor proliferation biomarker, research shows Ki-67 is not required for cell proliferation itself but is involved in processes essential for tumorigenesis and chromatin organization. There are currently no drugs known to directly bind, inhibit, or modulate Ki-67.

Other names

MKI67Antigen Ki-67Marker of proliferation Ki-67Antigen Kiel 67