TGFB1 and Alzheimer disease: Specifically, peripheral blockade of the TGF-β-Smad 2/3 signaling pathway leads to brain penetration of peripheral macrophages and amelioration of the defining pathology of AD—β-amyloid plaques—in the Tg2576 transgenic mouse model of cerebral amyloidosis (Town et al., 2008; Rezai-Zadeh et al., 2009; Town, 2009; Gate et al., 2010).