CREB3 is expressed ubiquitously (Lu et al. 1997) and associates in the endoplasmic reticulum (ER) membrane (Stirling and O'Hare 2006) with DCSTAMP (Eleveld-Trancikova et al. 2010). Through an unclear mechanism, that may involve association of OS9 with unfolded proteins, CREB3 and DCSTAMP, which may remain in a complex, transit from the ER membrane to the Golgi membrane where CREB3 is activated by cleavage (Eleveld-Trancikova et al. 2010). CREB3 becomes activated during maturation of dendritic cells induced by lipopolysaccharide and cytokines (Eleveld-Trancikova et al. 2010).