MYCN and neoplasm: Immunohistochemistry on neuroblastoma tissue-microarrays (TMAs) containing 47 neuroblastic tumor patient cores of different stages revealed that BMP4 expression was markedly restricted to tumors with more differentiation (ganglioneuroblastoma and ganglioneuroma), with virtually no expression of BMP4 evident in poorly differentiated neuroblastomas, including both MYCN amplified and non-amplified tumors (Figure 4A–C).