The targeting vector contains a loxP-flanked PGKneo cassette downstream of Biotin-3xFLAG (BioFL) sequence (encoding a biotin recognition motif and 3 copies of the FLAG epitope) fused to the C-terminus of the gene. Cre-mediated recombination removed the floxed neo cassette. Western blotting detected levels of Rnx2-BioFL protein similar to wild-type. (J:328555)