Table 2.

Major ECMs in vascular basement membrane

ECM	Class	Structure	Size	Primary crosstalk	Expression in GBM stroma	Primary functions in BBB and GBM	Ref.
Laminin	Glycoprotein	Trimeric protein with α, β and γ chains	~400 kDa	α1β1 and α6β1 integrin, HSPG, TSP-1, nidogen	-	BMEC differentiation; BBB integrity; GSC survival	[39,81–83]
Fibronectin	Insoluble glycoprotein	Dimer connected through disulfide bonds	440 kDa	α5β1 integrin, fibrin, collagen, gelatin, TSP-1	Increased	Cell adhesion, cohesion, and invasion	[39,70,76]
Perlecan	HSPG2	Core protein with three GAG chains attached	~500 kDa (core protein)	Nidogen, fibronectin, collagen IV heparin, heparin-binding growth factors	Increased	Tumor angiogenesis, biomechanical properties of BM	[39,81,195]
Type IV collagen	Protein	Trimeric with three α chains	~180 kDa (each monomer)	Fibronectin, perlecan, nidogen	Increased (localized to BM)	Angiogenesis; structural support to vascular BM	[39,81]
Nidogen (entactin)	Glycoprotein	Three globular subdomains	139 kDa	Collagen IV, perlecan, laminin, integrin	-	Collagen IV-laminin network stabilization	[81,197]
Vitronectin	Glycoprotein	Two polypeptides linked by disulfide bonds	75 kDa	αvβ5 and αvβ3 integrins, PAI-1, antithrombin III	Increased	Microglia activation; tumor malignancy	[75,82,198]