RELA and infection: However, the utilization of HCMV mutants lacking the NFκB motifs in the MIEP did not result in significant attenuation of infection or IE gene product accumulation [96], suggesting that additional host transcription factor binding motifs present in the MIEP, including CREB (cAMP response element binding) and ATF (activating transcription factor) sites [97], may be sufficient to activate IE gene transcription even in the absence of p65/p50 binding.