Plv ef1a ires blast vector

APEX2 was PCR amplified from pcDNA3-APEX2-NES, a kind gift from the laboratory of Kendall Blumer at Washington University in St. Louis. ADAR1-p110 was PCR amplified from pLVX-p110-ADAR1 described previously^{33 (link)}. APEX2 and p110 were cloned into pLVX-IRES-puro (Takara, 632183) via a series of restriction enzyme digests and ligations. The final plasmids pLVX-3xFLAG-APEX2 and pLVX-3xFLAG-APEX2-linker-p110 were confirmed by digestion and sequencing. The linker consists of three repeats of Gly-Gly-Gly-Gly-Ser. Lentiviral shRNA constructs in the pLKO.1-puro vector were purchased as glycerol stocks from Millipore Sigma (Supplemental Table 1). For shADAR1, the shRNA was subcloned into pLKO.1-hygro (Addgene, #24150). Overexpression constructs for DHX9 and ADAR were generated by PCR amplification and ligation into pLV-EF1a-IRES-Blast vector (Addgene, #85133). For DHX9 overexpression, wobble mutants were made to reduce shRNA targeting. Mutagenesis primers for DHX9 K417R and shRNA-resistant codons (designed using the Synonymous Mutation Generator^{64 (link)}) are included in Supplemental Table 1. The DHX9-dsRBD-EGFP construct was generated by digestion of pLV-EF1-DHX9 with SpeI and EcoRI and ligation of EGFP in place of the 3’ portion of DHX9. The resulting construct codes for the first 344 amino acids of DHX9 fused to EGFP.