The enhancement effect of SENP-1 on PR transcriptional activity requires full-length PR-B but not the PR DBD. HeLa cells were transfected with the PRE2-Luc (A and B) or ERE2-Luc (C and D) reporter plasmids in the presence of pSV40-Renilla as internal control along with NT-B (A), PR DBD-LBD (B), a PR-B specificity mutant containing the ER DBD (C) or wild-type ER (D) expression vectors, and SENP1 or SENP1m (A, right panel) expression vectors at doses of 20, 50, 100, 200 and 1000 ng of DNA or an empty vector control (-). Cells were treated without (-) or with (+) 10 nM R5020 (A and C) or 1 nM 17β-estradiol (E2) (D) for 24 hrs before being assayed for luciferase activity. The values are expressed as relative luciferase units normalized to Renilla controls. Statistical significance was computed by unpaired student's t test. *p < 0.05.