“…The trimeric CAK complex in metazoans appears to be multi-functional; it is required for CDK activation through threonine phosphorylation in their T-loop regions (Larochelle et al, 1998;Harper and Elledge, 1998), and is also involved in the regulation of transcription both as free CAK complex and as a component of the general transcription factor TFIIH (Feaver et al, 1994;Roy et al, 1994;Serizawa et al, 1995;Shiekhattar et al, 1995;Adamczewski et al, 1996) through phosphorylation of the RNAP II CTD and a number of general and regulatory transcription factors. These include the GTFs TBP, TFIIEa, TFIIFa (Ohkuma and Roeder, 1994;Yankulov and Bentley, 1997), Oct transcription factors (Inamoto et al, 1997), p53 (Ko et al, 1997), retinoic receptor alpha (RARa) (Rochette-Egly et al, 1997), estrogen receptor alpha (ERa) (Chen et al, 2000), and pRb (Wu et al, 2001).…”