| The mitogen activated protein kinase interacting kinase 1 ( Mnk 1 ) is phosphorylated by caspase cleaved protein kinase Pak2 / gamma PAK but not by Cdc 42 activated Pak 2 . ^^^ Phosphorylation of Mnk 1 is rapid , reaching 1 mol / mol within 15 min of incubation with Pak 2 . ^^^ A kinetic analysis of the phosphorylation of Mnk 1 by Pak 2 yields a K ( m ) of 0 . 6 microm and a 5 ( max ) of 14 . 9 pmol of ( 32 ) P / min / microg of Pak 2 . ^^^ Two dimensional tryptic phosphopeptide mapping of Mnk 1 phosphorylated by Pak 2 yields two distinct phosphopeptides . ^^^ Phosphorylation of Mnk 1 by Pak 2 does not activate Mnk 1 , as measured with either eIF4E or eIF4F as substrate . ^^^ |