part_of RNA polymerase II transcription pathway RNA polymerase II transcription elongation pathway 2013-06-03T09:19:50Z PW:0001331 RNA Polymerase II Transcription Elongation RNA polymerase II transcription elongation commences when the nascent transcript reaches about 25 residues. Some general transcription factors are released and the RNA polymerase II carries out elongation of the pre-mRNA transcript and proofreading. Various regulators control early elongation, proximal promoter pausing and full elongation proceedings. Nascent mRNA processing, splicing and alternative splicing are co-occurring. pathway transcription elongation by RNA polymerase II promoter vpetri