| Interaction between cyclin T 1 and SCF ( SKP 2 ) targets CDK 9 for ubiquitination and degradation by the proteasome . ^^^ SCF ( SKP 2 ) was recruited to CDK9 / cyclin T 1 via cyclin T 1 in an interaction requiring its PEST domain . ^^^ CDK 9 ubiquitination was modulated by cyclin T 1 and p 45 ( SKP 2 ) . ^^^ We propose a novel mechanism whereby recruitment of SCF ( SKP 2 ) is mediated by cyclin T 1 while ubiquitination occurs exclusively on CDK9 . . ^^^ |