VPC 23019, an aryl amide-containing Sphingosine 1-phosphate (S1P) analog, is a competitive antagonist at the S1P1 and S1P3 receptors (pKi= 7.86 and 5.93, respectively) and an agonist at the S1P4 and S1P5 receptors (pEC50= 6.58 and 7.07, respectively).