We inserted an EF1α basal promoter fragment into HindIII and NheI sites of the multiple cloning site in pGL4.10 (Promega) to construct a basal pGL4.10EF1α backbone. We next removed the the BamHI and SalI containing fragment located at downstream of the SV40 late poly(A) signal of the original pGL4.10 vector backbone, and re-inserted the fragment at the SpeI site that is located upstream of the synthetic poly(A) signal/transcriptional pause site to generate modified versions of pGL4.10EF1α and pGL4.10 (see Supplementary Figure 9d).
