We have constructed pUCSV0cat with low background of chloramphenicol acetyltransferase (CAT) activity and pUCSV3cat (positive control), both containing a SV40 polyadenylation signal 5' to the CAT-coding gene and to the SV40 promoter, respectively. Using this modified pUCSV0cat, we found that human embryonic 293 cells have the ability to activate the promoter of the human renin gene. In addition, we identified the cis-acting sequences responsible for cell-specific expression of the human angiotensinogen gene in its 5'-flanking region.