p-Cresol sulfate-d4 (potassium) is deuterium labeled p-Cresyl sulfate (potassium). p-Cresyl sulfate potassium is a uremic toxin that binds to a prototype protein. p-Cresyl sulfate potassium activates the JNK and p38 MAPK signaling pathways. p-Cresyl sulfate potassium has pro-inflammatory activity[1][2][3].