CLDN5 and Cerebral ischemia: Since the degradation of claudin-5 and ZO-1 are highly correlated with the dynamic process of BBB break down following cerebral ischemia [9,10,26], the reduced expression of tight junction proteins claudin-5 and ZO-1 in the MCPIP–/– mice after cerebral I/R may contribute to the BBB disruption, leading to enhanced extravasation of FITC-dextran seen in the MCPIP–/– mice (Figure 5).