GHRH and neoplasm: Proliferation of some human cancers in vitro is stimulated by exogenous GHRH and suppressed by GHRH antagonists or GHRH anti-sera.[44] Studies suggest that dysregulation of GHRH expression or autocrine/paracrine secretion contributes to the pathogenesis of breast and other cancers.[45] In vivo studies have demonstrated the anti-tumor activity of GHRH antagonists against multiple cancer types.