GFP expression and number of integrants in cells exposed to SIN lentiviral vectors. (a) MFI of MDTF cells exposed to RRLSINpgkGFP or RRLSINΔpgkGFP vectors as measured by flow cytometry. (b) Proviral integrants copy number. qPCR were used with GFP specific primers to determine the copy number of vectors per MDTF cell exposed to RRLSINpgkGFP or RRLSINΔpgkGFP vectors. (c) Relative GFP mRNA level of MDTF cells exposed to RT43.2GFP, RRLSINpgkGFP or RRLSINΔpgkGFP. All results are depicted as mean ± SEM, n = 3. GFP, green fluorescent protein; MDTF, Mus dunni tail fibroblast; MFI, mean fluorescence intensity; mRNA, messenger RNA; SIN vectors, self-inactivating vectors.