Fig. 7. mSTI1 is phosphorylated in vitro at multiple sites by cdc2 kinase. In vitro cdc2 kinase assays were incubated for 3 hours and 9 hours using purified recombinant mSTI1 and its modified derivatives (5 µM). The phosphorylated proteins were resolved by SDS-PAGE and the radioactive phosphorylation in the dried gel was detected by autoradiography.