In this paper, the human phosphodiesterase 7A1 (h PDE7A1 ) promoter region was identified and functionally characterized. Transient transfection experiments indicated that a 2.9 kb fragment of the h PDE7A1 5'-flanking region, to position -2907, has strong promoter activity in Jurkat T-cells. Deletion analysis showed that the proximal region, up to position -988, contains major cis -regulatory elements of the h PDE7A1 promoter. This minimal promoter region contains a regulatory CpG island which is essential for promoter activity. The CpG island contains three potential cAMP-response-element-binding protein (CREB)-binding sites that, as judged by in vivo dimethyl sulphate (DMS) footprinting, are occupied in Jurkat T-cells. Moreover, over-expression of CREB results in increased promoter activity, but, on the other hand, promoter activity decreases when a dominant-negative form of CREB (KCREB) is over-expressed. In vivo DMS footprinting strongly indicates that other transcription factors, such Ets-2, nuclear factor of activated T-cells 1 (NFAT-1) and nuclear factor kappaB (NF-kappaB), might also contribute to the regulation of h PDE7A1 promoter. Finally, h PDE7A1 promoter was found to be induced by treatment with PMA, but not by treatment with dibutyryl cAMP or forskolin. These results provide insights into the factors and mechanisms that regulate expression of the h PDE7A gene.