IL-7 enhances the transcriptional activities of NFAT and AP-1. Human T lymphocytes, prestimulated as described in the Materials and Methods section, and the T-leukemia Jurkat cell line were transfected with 20 μg of (A) pCAT3e-3 × NFAT/IL-2, a CAT reporter construct under the control of three copies of the distal NFAT site from the human IL-2 promoter, or (B) pCAT-3 × AP-1/IL-2, a CAT reporter construct driven by three copies of the AP-1 site from the IL-2 promoter. Transfected cells were left alone for 1 hour, divided in four groups and subsequently left unstimulated or stimulated with IL-7 alone, PHA alone or PHA plus IL-7 for 24 hours. CAT expression was measured as described in Materials and Methods. The results are expressed as the relative CAT expression compared to the PHA-induced CAT expression, which was set at 1. The IL-7–induced CAT expression in Jurkat cells was not determined (ND). The mean found for the relative CAT expression in three to six independent experiments is shown.