Probable regulator of CREB1 transcriptional activity which is involved in adipose cells differentiation. May also play a regulatory role in the cell cycle. Interacts with CREB1; regulates CREB1 phosphorylation, stability and transcriptional activity (By similarity). Interacts with immediate-early (IE) protein BICP22 of bovine herpesvirus-1 (BHV-1). Phosphorylated by AMPK. Belongs to the bZIP family. ATF subfamily.