GCSF is induced in macrophages in response to bacterial endotoxin, i.e., lipopolysaccharide. The promoter region of human and mouse GCSF genes is highly homologous up to 300 bp from the transcription initiation site. E. coli chloramphenicol acetyltransferase (CAT) assay of various mutants in the 300-bp promoter of the mouse GCSF gene suggested that at least 3 cis-controlling elements are required for gene expression: GCSF promoter elements (GPE) 1 through 3. Nishizawa et al. (1991) isolated cDNAs encoding mouse GPE1-binding protein. A 150-amino acid protein deduced from the cDNA has a basic domain and a leucine zipper motif and seems to be identical to the protein that binds to the enhancer element of immunoglobulin (Roman et al., 1990). See 147141.