ENO2 and neuroblastoma: While normally developing human sympathetic neuroblasts appear to express a given set of genes in a co-ordinated and repeated fashion between embryos (30), only a subset of the same set of genes is usually expressed in a given tumor, and this subset can differ from one tumor to another and between tumor cells within a tumor as exemplified by the neuron-specific enolase (ENO2) expression (in neuroblastoma and ganglioma, the differentiated form of neuroblastoma) (Figure 2) (31).