Wild-Type But Not Phospho-Mutant S345A PR-B Is Recruited to the p21 Promoter
A, T47D cells stably expressing wt, S345A, or mPro PR-B were treated for 60 min with vehicle, R5020, or R5020 and RU486 before ChIP with Ab for PR, Sp1, or rabbit IgG for a specificity control. PCR were carried out using primers spanning the p21 promoter proximal GC-rich Sp1 response element (RE) or a control distal element (DE) and visualized by ethidium bromide staining of agarose gels. B, HeLa cells transiently transfected with either wt or S345A PR-B were treated for 60 min with vehicle or R5020 and subjected to ChIP with PR Ab or rabbit IgG. PCR using primers specific for the p21 promoter Sp1 (RE) or (DE) were visualized as in A. Results were repeated at least three times with similar results.