YM-254890 is a selective Gαq/11 protein inhibitor isolated from Chromobacterium sp. YM-254890 shows no inhibition of other G protein subtypes. YM-254890 inhibits platelet aggregation induced by ADP by blocking the P2Y1 signal transduction pathway, with an IC50 value below 0.6 μM[2].IC50 & Target:Gαq/11 protein[2]In Vitro: YM-254890 inhibits platelet aggregation induced by ADP (2, 5 and 20 μM) in human platelet-rich plasma with IC50 values of 0.37, 0.39 and 0.51 μM. ADP mediates platelet aggregation via two G protein-coupled receptors, P2Y1 and P2Y12. The effect of YM-254890 on the P2Y1 and P2Y12 signal transduction pathways using C6-15 cells stably expressing the human P2Y1 or P2Y12 receptors is examined. Stimulation of P2Y1-C6-15 cells by 2MeSADP leads to increases in intracellular calcium mobilization. In this assay, YM-254890 inhibits the increase in [Ca2+]i with an IC50 value of 0.031 μM. In contrast, 2MeSADP-induced inhibition of forskolin-stimulated adenylyl cyclase activity in P2Y12-C6-15 cells is unaffected by YM-254890 at 40 μM.