Generation and characterization of BAC transgenes encoding full-length or truncated CX3CL1 isoforms. (A) Schematic of homologous recombination strategy involving pDelSac shuttle vector to replace exon 3 of the CX3CL1 gene in the BAC RP24–147I16 with a fragment harboring a silent mutation and creating a XhoI site (CX3CL1395AA) or a truncated myc-tagged CX3CL1 exon (CX3CL1105Δ). (B) Analysis of transgene expression in intestinal tissue by RT-PCR analysis of ileal tissue of CX3CL1105Δ BAC transgenic mice. (C) Western blot analysis of intestinal epithelial cell fraction of CX3CL1105Δ BAC transgenic mice WT littermates using anti-myc antibody (9E10). Note that the 15-kDa band that is specific for the transgenic tissue-derived sample and probably represents the myc-tagged CX3CL1105Δ protein.