A complex first isolated from eggs of Xenopus laevis (q.v.). Immature oocytes are normally blocked in the G2 stage of the cell cycle (q.v.). However, when the cells are injected with MPF, they proceed through mitosis and stop at the transition between metaphase and anaphase. The MPF causes chromosomal condensation, breakdown of the nuclear envelope, and the inhibition of transcription during mitosis. For these reasons, MPF is often called the mitosis promoting factor. This factor is now known to contain two subunits: a protein kinase and a cyclin (both of which see). Also see Chronology, 1971, Masui and Smith; cell division genes, checkpoint, p34 (CDC2).
Subjects: Genetics and Genomics.