AQP4 and amyotrophic lateral sclerosis: Using our within-case analysis approach we found no change between leaked and non-leaked regions of individual ALS cords, in endothelial junction proteins claudin-5 and ZO-1 or the efflux protein P-glycoprotein, or in the perivascular astrocyte endfeet marker aquaporin 4, that regulate BSCB tightness.