Clone REA1123 recognizes the human, mouse and rat Ki-67 antigen, a nuclear and nucleolar protein, which is strictly associated with cell proliferation. Two Ki-67 isoforms with molecular weight, 395 and 345 kDa are known. Both isoforms contain 16 “Ki-67 repeat“ sequences, each of which includes a conserved 66 bp “Ki-67 motif“. Expression of Ki-67 protein is present during all active phases of the cell cycle (G(1), S, G(2), and mitosis), but is absent from resting cells (G(0)). Due to strict association of Ki-67 with proliferating cells, Ki-67 is often used as an indicator of the “growth fraction“ of a given cell population. The N-terminal portion of Ki-67 contains a forkhead associated (FHA)1 domain, which is involved in interaction with proteins such as Hklp2 and NIFK.

Additional information: Clone REA1123 displays negligible binding to Fc receptors.