transcription elongation factor complex DSIF complex A heterodimeric protein complex formed of Spt4 and Spt5 proteins which is expressed in eukaryotes from yeast to man. DSIF is an inhibitory elongation factor that promotes RNA polymerase II transcriptional pausing, but can also stimulate transcriptional elongation under certain conditions, and may play a role in RNA processing via its physical association with mRNA capping enzymes. Spt4-Spt5 complex DRB sensitivity inducing factor complex cellular_component 5,6-Dichloro-1-beta-D-ribofuranosylbenzimidazole sensitivity inducing factor complex Spt5-Spt4 complex GO:0032044