| As the cdc 2 kinase is specifically active during mitosis , we sought to investigate whether it actually phosphorylates Rap1GAP during this phase of the cell cycle . ^^^ We show that p34cdc2 co immunoprecipitated from mitotic Hela cell lysates with an anti human cyclin B 1 antibody , but not from interphasic cell lysates , is able to phosphorylate efficiently wild type Rap1GAP , but not a mutant in which the putative consensus site for phosphorylation by the cdc 2 kinase ( serine 484 ) has been altered . ^^^ These results therefore strongly suggest that Rap1GAP is indeed a substrate of the cdc 2 kinase during mitosis . ^^^ |