CDK6 and ischemia: Double immunofluorescence staining revealed that cyclin D1/CDK6 was co‐localized with TUNEL‐positive cells in the penumbral tissue of vehicle‐treated MCAO rats after 90 min of ischemia and 24 h of reperfusion (Figure 6A–D), indicating that ischemia‐induced neuronal apoptosis is closely associated with the upregulation of cyclin D1 and CDK6 expression.