CREBZF strongly activates transcription when bound to HCFC1. CREBZF suppresses the expression of HSV proteins in cells infected with the virus in a HCFC1-dependent manner. It also suppresses the HCFC1-dependent transcriptional activation by CREB3 and reduces the amount of CREB3 in the cell. It is able to down-regulate expression of some cellular genes in CREBZF-expressing cells.