Notes: Sp-Uridine-5'-O-(1-thiotriphosphate) (Sp-UTP-α-S) is a nucleotide agonist of the purinergic Y2 (P2Y2) and P2Y4 receptors.{66461}. It induces inositol phosphate accumulation in 1321N1 astrocytoma cells expressing the purinergic P2Y2 or P2Y4 receptors (EC50s = 14 and 81 µM, respectively).