In comparison to wild-type gD, a mutated form of gD that was unable to bind to HVEM did not stimulate NF-KB activity in cocultured monocytoid cells [9] . HEp-2 cells, which do not express HVEM, lacked detectable NF-kB signalling after infection with UV-inactivated HSV-1, implying that gD-mediated NF-kB stimulation may be dependent on expression of HVEM [9] .