Schematics showing the design of indicated lentivectors. LTR, self-inactivating long-term repeats; MNDU3, internal promoter derived from the MND retroviral LTR U3 region; , packaging signal with the splicing donor and splicing acceptor sites; RRE, reverse-responsive element; cPPT, central polypurine tract; WPRE, woodchuck responsive element.
