Anti-CREB pS133 antibody reacts with phosphorylated human CREB at pS133 and shows minimal reactivity by western blot with non-phosphorylated CREB and minimal reactivity (1%) by ELISA against the non-phosphorylated form of the immunizing peptide. This antibody was assayed against a variety of tissues including fibroblasts and B-cell lysates. Bands of 46 and 43 kDa corresponding to phosphorylated CREB are observed in western blots. Anti-CREB pS133 is suitable for the detection by immunoblot of phosphorylated human, mouse and rat CREB. No cross-reactivity occurs with non-phosphorylated CREB. For immunohistochemistry, formalin fixed, paraffin embedded human tissue shows moderate to strong nuclear staining in a variety of cells with minimal background staining. Although not tested this antibody is likely functional by FACS and immunoprecipitation.