The betaIII isoform of tubulin is present dominantly in cells of neuronal origin and it is one of the earliest markers of neuronal differentiation. It is regarded as a specific probe for the cells of neuronal origin as well as for the tumours originating from these cells. The betaIII-tubulin is most abundant in cells of neuronal origin, but was also detected in Sertoli cells of the testis and transiently in non-neuronal embryonic tissues.