RSPO3 and hereditary pheochromocytoma-paraganglioma: Functional studies, overexpression and silencing of LGR5 and treatment with its cognate ligand R-spondin-3, were performed on either the immortalized human adrenocortical H295R cell line or normal primary adrenal cells cultured from adrenalectomized adrenals of patients diagnosed with either primary hyperaldosteronism or pheochromocytoma.