CSF extract was supplemented with Flag-Cdc20 wt IVT coupled to α-Flag beads. Calcium was added and Flag-Cdc20 was isolated by α-Flag immunoprecipitation at the indicated time points. Input and pellet (IP: Flag) samples were immunoblotted for the Flag-tag, pThr68 Cdc20 and p150(Glued). The pThr68 Cdc20 membrane was stripped and reprobed for cyclin B2. Asterisk in the cyclin B2 immunoblot indicates the IgG heavy chain. Asterisks in other immunoblots indicate unspecific bands. 