Fig. 3.

CDK9 sumoylation inhibits formation of the P-TEFb complex. a HEK293T cells were transfected with PIAS1 and/or SUMO-1 as indicated and the global levels of sumoylation were analyzed by WB blotting using an anti-SUMO-1 antibody as indicated. b-e The effect of PIAS1 and/or SUMO-1 expression on the formation of the P-TEFb complex was analyzed by IP using anti-CDK9 (b), anti-Cyc T1 (c) and anti-Hexim1 (d), followed by WB using antibodies as indicated. In addition, the effect on association of 7SK snRNA was assayed by RT-PCR (e). f Diagram illustrating that CDK9 sumoylation blocks the formation of P-TEFb complex