TEK and glioma: To better mimic the in situ tumor confining and allow the contact with 3D matrix, we generated 3D cultures of U251.vector and U251.Tie2 cells in an enriched collagen I matrix since collagen I is one of the major components of the extracellular matrix of gliomas and the activation of Tie2 resulted in increased adhesion to this extracellular component [12].