It has also been suggested that gonococcal infection of the cervical epithelium requires the combined action of pilin, porin and iC3b (an opsonin and ligand for complement 3 receptor (CR3)) (Edwards et al., 2002), and that the pilin glycan is required for binding to iC3b and thus involved in activation of the CR3 (Jennings et al., 2011). Here, CRIPTO3 is linked to bacterial sexually transmitted disease.