Required. Matrigel containing phenol red is mainly caused by the interaction between phenol red and bicarbonate and CO2, so it needs to be hydrated. Corning Matrigel is a basement membrane matrix extracted from EHS mouse tumors rich in extracellular matrix proteins. Its main components include laminin, type IV collagen, nestin, heparin sulfate glycoprotein, growth factors and Matrix metalloproteinases, etc.