. "Cyclin A:Cdc2 complexes are detected in the nucleus earlier that cyclin B1:Cdc2 complexes and may play a role in the initial events in prophase. Inactivation of Cdc25B by proteasome-mediated degradation is dependent upon cyclin A:Cdc2-mediated phosphorylation (Cans et al, 1999)"^^ . . . . . . "Phosphorylation of proteins involved in the G2/M transition by Cyclin A:Cdc2 complexes"^^ . . . . . .