Carcinoembryonic antigen-related cell adhesion molecules belong to the immunoglobulin (Ig) superfamily. Several members of the CEACAM subgroup are expressed on human epithelial cells and include the widely expressed transmembrane CEACAM1 as well as GPI-anchored CEA and CEACAM6. All CEACAMs have an N-terminal IgV-like domain and variable numbers of IgC2-like A and B domains. CEACAM1 comprises up to four extracellular domains: N, A1, B and A2 and either a long or a short cytoplasmic tail (Tsutsumi et al., 1990; Prall et al., 1996; Hammarstrom, 1999) . Various functions have been attributed to CEACAM1 including cell-cell adhesion, insulin regulation and angiogenesis (Obrink, 1997; Hammarstrom, 1999; Wagener and Ergun, 2000; Najjar, 2002) . Targeting of CEACAMs by N. gonorrhoeae, as well as Nm and Hi leads to cellular invasion and passage across polarized monolayers (Virji et al., 1999; Gray-Owen, 2003; M. Soriani, K. Setchfield, D.J. Hill, and M. Virji, unpublished data) .