Liquid. In 100 mM NaCl, 50 mM Tris-HCl, 15 mM reduced glutathione, 5 mM DTT, 20% glycerol, pH 8.0. AVOID FREEZE/THAW CYCLES. Recombinant, human cyclin dependent kinase 4 (Cdk4) and recombinant, human cyclin D1 (CycD1), each fused to a GST-thrombin cleavage site sequence at their respective N-termini and co-expressed in S. frugiperda insect cells using a baculovirus expression system. MW: 59700(Cdk4) and 60000(cyclinD1). Specific activity: ≥91 U/mg protein. One unit is defined as the amount of enzyme required to transfer 1 nmol phosphate to nto Rb-CTF per min at 30°C, using variable concentrations of ATP (100 nM to 17.7 µM). EC 2.7.1.112.

Ref.: Ji, J.Y., et al. 2005. Development 132, 2501.