CCR7 is a GPCR that binds to CC chemokine ligands MIP-3beta (ELC/CCL19) and 6Ckine (CCL21) (Yoshida et al., 1997). These ligands are expressed in the secondary lymphoid organs, and binding to CCR7 expressed in naïve T cells, B cells and dendritic cells directs migration of these cells to sites of antigen presentation (Förster et al., 1999). Inhibition of CCR7/ligand interactions inhibits contact sensitivity, delayed type hypersensitivity, and graft vs host disease in experimental models (Förster et al., 1999; Sasaki et al. 2003). In addition, CCR7 expression by breast cancer, melanoma and other malignant cells are associated with lymph node metastasis (Muller et al., 2001; Payne and Cornelius, 2002). Chemicon's cloned human CCR7-expressing cell line is made in the Chem-2 host, which supports high levels of recombinant CCR7 expression on the cell surface and contains high levels of the promiscuous G protein Galpha16 to couple the receptor to the calcium signaling pathway. Thus, the cell line is an ideal tool for screening for antagonists of interactions between CCR7 and its ligands.