COL1A1 and Stroke: Transcription factor CoupTF2 (Fig. 2D–F, nuclear) was expressed by the Col1a1+ meninges (Fig. 2D, carets) and by Col1a1+ PSCs at P0 (Fig. 2D, arrows), P21 (Fig. 2E, arrows) and in the stroke lesion by PDGFrβ+ PSCs (Fig. 2F, arrows) but not by Ib4+ macrophages (Fig. 2F, carets).