“…This response is divided into two stages; within minutes, a rapid primary response independent of new protein synthesis is initiated, which instructs the downstream translationdependent secondary response (2,5). Many primary response genes have active chromatin marks and features of transcriptional pausing, including high occupancy of the initiating form of RNA polymerase II (RNAPII), S5 phosphorylated (S5P) (2,4,6), along with negative elongation factor complex (NELF) and DRB Sensitivity-Inducing Factor complex (DSIF), which prevent transcriptional elongation (4,(6)(7)(8)(9)(10). Paused RNAPII can be activated by the positive transcription elongation factor b (P-TEFb) in a stimulusdependent manner, which phosphorylates NELF, DSIF, and RNAPII to release the pause and promote transcriptional elongation and thus the production of mature mRNAs (9,(11)(12)(13).…”