Effect of Growth Hormone-Releasing Peptide-2 (GHRP-2) and GH-Releasing Hormone (GHRH) on the cAMP Levels and GH Release from Cultured Acromegalic Tumours: Effect of Growth Hormone-Releasing Peptide-2 (GHRP-2) and GH-Releasing Hormone (GHRH) on the cAMP Levels and GH Release from Cultured Acromegalic Tumo