To investigate 20-kDa IL-1β signaling in brain endothelial cells, which are known to respond to IL-1β and contribute to the inflammatory response in central nervous system disorders (20), samples from a 8-h incubation of pro-IL-1β with cathepsin D and/or caspase-1 were added to the mouse brain endothelial cell line, bEnd.5, for 60 min before being replaced with serum free media for a further 23 h. Here, CTSD is linked to central nervous system disorder.