Schematic representation of the lentiviral vectors used in this study (not to scale). Schematic structure of the lentiviral vectors expressing eGFP (LvGFP), hemagglutinin (LvHA), or the murine preproinsulin-2 (LvPpins2). The size of the inserts is indicated on the figure. RSV-U3 indicates U3 promoter/enhancer of the Rous sarcoma virus; SD, splice donor; SA, splice acceptor; psi (Ψ), packaging signal sequence; ga-RRE, truncated gag gene with the rev responsive element; cppT, central polypurine tract; PGK, phospho-glycerate kinase promoter; WPRE, woodchuck hepatitis virus regulatory element; and LTR-SIN, self-inactivating long terminal repeat.