Figure 1. Expression of gastrin-releasing peptide receptor (GRP-R) in neuroblastomas. Two representative histologic sections from each of three subtypes of neuroblastomas showing differential GRP-R expression by immunohistochemical staining (×100). Increased expression of GRP-R protein (shown by the brown staining) is noted in undifferentiated neuroblastomas compared with glioneuroblastomas or ganglioneuromas.