Silver’s group reported subsequently that phosphate, like calcium, regulates pre-pro-PTH gene expression post-transcriptionally by changes in protein-PTH mRNA interactions at the 3′-UTR which determine PTH mRNA stability. The authors identified the minimal sequence required for protein binding in the PTH mRNA 3′-UTR and determined its functionality. They found that the conserved PTH RNA protein-binding region conferred responsiveness to calcium and phosphate and determined PTH mRNA stability and levels (127). Thus, a low calcium diet increased stability, whereas a low phosphate diet decreased stability of PTH mRNA (128) (Figure 11). The PTH mRNA 3’-untranslated region-binding protein was subsequently identified by this research group as adenylate-uridylate-rich element RNA binding protein 1 (AUF1) (129).