Fig. 1.

Cdk9 is not required for promoter-proximal pause escape. a Western blot analysis using antibodies that specifically recognize pSpt5 compared with total Spt5 in wt and cdk9^as over a time course of cultures treated with 10 μM 3-MB-PP1. Total Spt5 represents both phosphorylated and unphosphorylated forms. Tubulin serves as a loading control. b TSS-centered composite profiles of PRO-seq data before (blue) and after (red) 5 min of treatment with 10 μM 3-MB-PP1 for genes grouped by quartiles of increasing pausing index from left to right (calculated using untreated wild-type data from combined replicates). The top four panels represent wild-type data, while the bottom four panels represent cdk9^as data. Each quartile contains 841 filtered genes. c Cumulative density functions for pausing index (log₁₀) of all filtered genes in treated (red) and untreated (blue) samples for the cdk9^as strain. Data used in b and c reflect the results of combined data from two biological replicates for each treatment