(S)-3-aMino-4-(3-hexylphenylaMino)-4-oxobutylphosphonic acid (TFA salt)

W140 is the inactive enantiomer of the sphingosine-1-phosphate receptor 1 (S1P₁) antagonist W146 .¹ It only weakly binds to S1P₁ (K_i = 4.6 μM for the human receptor). W140 has been used as a negative control in vitro and in vivo in the study of S1P₁ signaling.^1,2

1. Sanna, M.G., Wang, S.K., Gonzalez-Cabrera, P.J., et al. Enhancement of capillary leakage and restoration of lymphocyte egress by a chiral S1P₁ antagonist in vivo Nat. Chem. Biol. 2(8),434-441(2006).
2. Li, C., Chi, X.X., Xie, W., et al. Sphingosine 1-phosphate receptor 2 antagonist JTE-013 increases the excitability of sensory neurons independently of the receptor J. Neurophysiol. 108(5),1473-1483(2012).