SPP1 and Stroke: In view of the role of osteopontin and its receptor CD44 in stroke and BBB pathology, we first examined the time course of osteopontin and CD44 receptor expression in NVU cells in the peri-infarct region (Fig. 1) and infarct core (Supplementary Fig. S1) during the acute phase of ischemic stroke, including the early acute (4 h post-tMCAO) and late acute phase (15 and 24 h post-tMCAO).