The following elements were inserted 2 kb 5' of Ubb via homologous recombination: CMV enhancer/beta-actin promoter (CAG), loxP site, nuclear-localized beta-galactosidase/neomycin resistance protein reporter (NLS-beta-geo), 3 stop transcription sites, loxP site, tdTomato/Tobacco etch virus protease (TEVP), a 6xMyc epitope, a TEVP cleavage site, synaptic vesicle protein 2B (SV2B), GFP, 3xHA (hemagluttinin) epitope, rabbit beta-globin 3' UTR. (J:167667)