The fs-TRAP targeting vector was designed with, from 5' to 3', a CMV-IE enhancer/chicken beta-actin/rabbit beta-globin hybrid promoter (from pCAGGS), a floxed-neomycin (neo) resistance cassette and polyadenylation (polyA) sequence, a frt-flanked enhanced green fluorescence protein (EGFP)-L10a (ribosomal protein) fusion protein, a 2xHA (hemagglutinin) tagged bacterial birA, bifunctional protein (biotin ligase), gene, and a polyA sequence. This targeting vector was inserted into the Gt(ROSA)26Sor gene. (J:201159)