The basal lamina and extracellular matrix (ECM) in the intercellular substance is important structure in keeping the integrity of the BBB. Matrix metalloproteinase (MMP) is a family of proteolyticthe enzyme which can resolve the ECM.

• 基质金属蛋白酶（Matrix Metalloproteinase, MMP）是一组钙锌依赖性肽链内切酶家族，是分解ECM分子的蛋白酶类中最重要的一种。