The function of CREBZF (CREB/ATF bZIP transcription factor, ENSG00000137504) is as follows. Strongly activates transcription when bound to HCFC1. Suppresses the expression of HSV proteins in cells infected with the virus in a HCFC1-dependent manner. Also suppresses the HCFC1-dependent transcriptional activation by CREB3 and reduces the amount of CREB3 in the cell. Able to down-regulate expression of some cellular genes in CREBZF-expressing cells. {ECO:0000269|PubMed:10871379, ECO:0000269|PubMed:15705566}.