. "Full activity of most CDKs is dependent on CAK mediated phosphorylation at a conserved residue (Thr 161 in Cdc2). This modification is thought to improve substrate binding. High affinity binding of Cyclin A within the Cyclin A:Cdc2 complex requires this phosphorylation (Desai et al 1995)."^^ . . . . . . "CAK-mediated phosphorylation of Cyclin A:Cdc2 complexes"^^ . . . . .