Ki67

The Ki67 proteins were first discovered in an attempt to generate cancer specific monoclonal antibodies. 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.