sentences:  Further phosphorylation of Ser-2 causes recruitment of the RNA splicing machinery that catalyzes the removal of non-coding introns to generate mature mRNA.Alternative splicing expands the protein complements in eukaryotes.Just as with 5’-capping and splicing, the CTD tail is involved in recruiting enzymes responsible for 3’-polyadenylation, the final RNA processing event that is coupled with the termination of transcription.