CDC2-INDEPENDENT INDUCTION OF PREMATURE MITOSIS BY OKADAIC ACID IN HELA-CELLS

The induction of premature mitosis by okadaic acid (OA) in HeLa cells in S-phase or in G(2)-phase has been studied using light microscopy, i mmunofluorescence, and immunochemical techniques. The observations ind icate an involvement of a cdc2-independent pathway in these cells. It has been claimed that inhibition of an OA-sensitive phosphatase, possi bly of PP1, induces activation of a kinase which is sensitive to staur osporine and Zn2+. This kinase brings about mitosis-specific cytoskele tal rearrangements, chromosome condensation, and nuclear envelope brea kdown, inducing a mitosis-like state. However, other mitotic events do not follow. The possibility that this kinase may be a NIMA-like Nek2 kinase is discussed. (C) 1998 Academic Press.