HHEX and breast carcinoma: In prostate and breast epithelial cells, the regulation of Endoglin expression contributes to the control of cell motility by PRH.3 Moreover, over-expression of PRH in prostate cancer cells and breast cancer cells inhibits cell migration and inhibits the ability of prostate cancer cells to penetrate a layer of endothelial cells in in vitro extravasation experiments.3 Here we show that PRH is hyper-phosphorylated in BPH, prostatic adenocarcinoma and prostate cancer cell lines and that PRH phosphorylation in prostate cells is dependent on CK2 activity.