CD34 and central nervous system cancer: Apparently, the fifth described mechanism of glioma neovascularization involves the trans-differentiation of glioma cells into 3 immunophenotypes: (1) CD117+/CD34+/connexin43+/NeuroD1+ Tc immunophenotype; (2) SMA+/NG2+ Pc immunophenotype; and (3) a mixed, transitional Tc/Pc immunophenotype with CD13/CD117 and NG2/CD34 co-expression.