Astrocyte-derived L-serine was found to regulate interstitial D-serine levels and seizure activity in a process controlled by phosphoserine phosphatase (PSPH). We identified a potent PSPH inhibitor, WS974536,nd found that its systemic administration dramatically reduced the frequency of spontaneous epileptic discharges in mouse and cynomolgus monkey models of TLE. In the project. We studied the effect of WS974536 on astrocytes by proteomics.