Bacterial artificial chromosome (BAC) library (CHORI) was used to obtain a 120 kb BAC (#RP24147I16) containing the entire mouse Cx3cl1 (chemokine (C-X3-C motif) ligand 1) gene. This BAC was modified to place a nonsense mutation at amino acid 105, in exon 3, followed by a myc-tag. CCL22 and CCL17 sequences were removed from the BAC by restriction digest. The transgene encodes a secreted truncated protein lacking the mucin stalk. (J:178874)