The BAC clone RP23-63O21 containing the Slc1a3 (Glast) locus was modified by inserting a cre-SV40 polyA cassette in exon II at the site of the endogenous ATG codon. The construct was used to create FVB/N transgenic mice by standard procedures. Five separate founder lines were obtained, all giving similar results in lineage tracing experiments. No line numbers were specified. (J:160736)