TGFB1 and Cerebral ischemia: While the expressions of VEGF and TGF-β were undetectable in the brains of sham-operated rats, marked expressions of VEGF and increasing numbers of TGF-β-positive cells were observed in the border area within the ischemic core at 21 days following administration (i.e., 28 days after cerebral ischemia) (Fig. 4A,B).