KIT and neoplasm: From these data, we conclude that both TrkAIII tyrosine kinase activity and SOD2 promote the formation of larger SH-SY5Y cell tumour spheroids/spheroid aggregates, in association with increased SOD-2, CD117, Nestin, SOX-2 and Nanog mRNA expression, and that TrkAIII tyrosine kinase activity but not SOD2 promotes Nanog, Nestin and SOX2 neural stem cell marker expression in TrkAIII SH-SY5Y tumour spheroids.