CD44 and neoplasm: Similarly, we noted a dramatic increase in the expression of CD44, a receptor for hyaluronic acid, collagens, and matrix metalloproteinases (MMPs), SERPING1, a serine protease inhibitor that controls blood clotting and fibrinolysis, and VIM (vimentin), a marker of fibrosis, in the F(h) (vs. the F(−)) TBME, suggesting that the reactive astrocytes contribute to a fibrous tumor brain microenvironment (Fig. 6e).