Among the proteins recruited to polymerase are elongation factors, thus called because they stimulate transcription elongation.  There are different classes of elongation factors. Some factors can increase the overall rate of transcribing, some can help the polymerase through transient pausing sites, and some can assist the polymerase to transcribe through chromatin.  One of the elongation factors, P-TEFb , is particularly important.  P-TEFb phosphorylates the second residue (Ser-2) of the CTD repeats (YSPTSPS) of the bound Pol II. P-TEFb also phosphorylates and activates SPT5 and TAT-SF1. SPT5 is a universal transcription factor that helps recruit 5'-capping enzyme to Pol II with a CTD phosphorylated at Ser-5. TAF-SF1 recruits components of the RNA splicing machinery to the Ser-2 phosphorylated CTD. P-TEFb also helps suppress transient pausing of polymerase when it encounters certain sequences immediately following initiation. 
Many eukaryotes have long slender motile cytoplasmic projections, called flagella , or similar structures called cilia . Flagella and cilia are sometimes referred to as undulipodia ,  and are variously involved in movement, feeding, and sensation. They are composed mainly of tubulin . These are entirely distinct from prokaryotic flagellae. They are supported by a bundle of microtubules arising from a centriole , characteristically arranged as nine doublets surrounding two singlets. Flagella also may have hairs, or mastigonemes , and scales connecting membranes and internal rods. Their interior is continuous with the cell's cytoplasm .