Whereas CREB appears to be ubiquitously expressed, CREM expression is tightly regulated through cell-, tissue-and development-specific mechanisms. Thus, it is not surprising that CREM-mediated gene transcription has been extensively studied in cell systems that display selective expression of single CREM variants, such as male germ cells, cells of the adrenal and pituitary glands, and T lymphocytes. Table 1 summarizes CREM target genes in various cell systems; however, most of these findings were generated in vitro (see also Box 1).
