library_construction_protocol: Total RNA was extracted by the RNeasy Midi Kit following the manufacturer's instruction. Extracted RNA was subjected to DNase treatment. eGFP mRNA enrichment and elution were performed using biotinylated probes as in Lu et al (PMID: 33712590), and the mRNA was reverse transcribed to cDNA using SuperScript™ IV First-Strand Synthesis System with gene specific primer MPRA_v3_Amp2Sc_R, following the manufacturer's instruction. We assembled the MPRA libraries as in Lu et al  (PMID: 33712590) and Shook et al  (PMID: 38183988)