library_construction_protocol: Cell permeabilization, run-on, and RNA extraction were performed following Mahat et al. 2016 Nature Protocols. Total RNA was extracted using hot phenol approach as described. The RNA was base hydrolyzed and excess unincorporated biotin-NTPs were removed before undergoing on-bead library prep. On-bead library prep was performed following the instructions on Judd et al. 2020, Biorxiv (https://www.biorxiv.org/content/10.1101/2020.05.18.102277v1.abstract)