PRH is known to regulate cell proliferation in multiple cell types.1 PRH over-expression inhibits the proliferation of CML cells and we have shown that over-expression of CK2 abrogates the negative effects of PRH over-expression on these cells.2 Here we have shown that PRH over-expression inhibits the proliferation of normal immortalised prostate cells and prostate cancer cells. This evidence concerns the gene HHEX and Familial prostate cancer.