Figure 6

CDK12 truncations show diminished activity against the RNA Pol II CTD.
Comparison of in vitro kinase activity against a GST-CTD substrate by various CDK12 complexes and CDK9/Cyclin T1 (FL denotes full length proteins). A representative autoradiograph detecting 32P-GST-CTD product is shown together with a graphic representation of 3 biological replicates of each phosphorylation reaction.