A method for altering transcription in a cell comprising an amount of active CDK9/cyclin, comprises the steps of: (a) introducing in the cell an agent which modulates the amount of active CDK9/cyclin in the cell, and thereby alters transcription in the cell, wherein the agent comprises an RNA selected from the group consisting of an RNA aptamer that specifically binds CDK9/cyclin, a CDK9/cyclin-binding domain of 7SK RNA, a 7SK RNA-binding antisense 7SK RNA domain, and a 7SK RNA-specific RNAi, and (b) detecting a resultant altering of transcription in the cell.Methods for screening for an agent which modulates 7SK RNA-CDK9/cyclin binding generally comprise the steps of (a) incubating a mixture of 7SK RNA, CDK9/cyclin and a candidate agent under conditions wherein but for the presence of the agent, the 7SK RNA and CDK9/cyclin engage in a reference binding; and (b) detecting an agent-biased binding of the 7SK RNA to the CDK9/cyclin.