Table 1.

Relative activities of constructs expressed as a percentage relative to wild-type CDK4/cyclin D1

Construct	Activity relative to wild type, %
Wild type (CDK4/CycD1)	100
CDK4EET172Ph/CycD11–271	290
CDK4EET172D/CycD11–271	2
CDK4EET172A/CycD11–271	12
CDK4EET172Ph/CycD115–271	26
CDK4EET172A/CycD115–271	2
CDK2(T160Ph)/CycA	175

The relative activities of the constructs were determined by measuring the initial rates of reaction for each construct in the presence of 2 mΜ ATP. Rates were then normalized relative to the wild-type construct. CDK4_EE represents CDK4 with residues 42–48 replaced by Gly₄₂–Glu₄₃′–Glu₄₄′–Gly₄₈, the sequence found in CDK6. Ph represents phosphorylation of the indicated residue.