A targeting vector designed with (from 5' to 3') a splice acceptor site, a loxP-flanked Neo-STOP cassette, a cDNA sequence encoding RACDA (RacG12V; a mutant form of Rac1 rendered constitutively active by a glycine->valine substitution at amino acid 12]), an frt-flanked internal ribosomal entry site-enhanced green fluorescent protein cassette (IRES-EGFP), and bovine polyadenylation signal. This transgene construct was inserted between exons 1 and 2 of the Gt(ROSA)26Sor locus. (J:157297)