PAX5 and neuroblastoma: We here report that even though neuroblastoma cells express both Pax-5 and E-proteins, both suggested to be crucial co-activators for EBF target genes in pre-B cells, the cells do not express the pre-B cell restricted target genes mb-1 and CD19. The expression of the mb-1 gene could, however, be activated by treatment of the neuroblastoma cells with chromatin disrupting agents.