Given increased protein expression from the pPRLR construct compared to the hPRLR in CHO-K1 cells, we investigated whether this reflected differences at the level of transcription. CHO-K1 cells were transfected with equal amounts of pPRLR-MPFlag, pPRLR-LR2Flag, pPRLR-LR4Flag and hPRLR-Flag DNA prior to analyzing the level of mRNA expression by Sybr Green quantitative RT-PCR. These experiments revealed no difference between the expression levels of hPRLR mRNA compared to each of the pPRLR mRNAs (Fig. 3B; Student's t-tests; P > 0.2).