RGS5 and stroke disorder: Pericytes loss has been suggested in the literature to be a major contributor to the decrease in TJs14,39,46,47 and BBB breakdown after stroke.13,39 We have shown that deletion of RGS5 in pericytes in stroke protects TJs.23 Interestingly, Hayashi et al.48 observed the tightest barrier in an endothelial/pericyte co-culture model even in hypoxic conditions, but only when the cells were in contact.