Effects of transfection of human mPRα or mPRβ siRNAs into MDA-MB-468 cells on mPR expression and plasma membrane [3H]-P4 binding. A, D, RT-PCR detection of mPRα (A) and mPRβ (D) mRNA levels in control (CTL) and mPRα siRNA (si-mPRα) (A) or mPRβ siRNA (si-mPRβ) (D) -transfected cells. RT+ and −: positive and negative reverse transcription. B, E, Plasma membrane mPRα (B) and mPRβ (E) protein levels of cells transfected with CTL and mPR siRNA oligos. *: p<0.05 compared to CTL. C, F, [3H]-P4 specific binding to plasma membrane of CTL and mPR siRNA oligo-transfected cells. ***: p<0.001 compared to CTL. N=3.