FTY720 (S)-Phosphate is an agonist of S1PR1. FTY720 (S)-Phosphate (Tys, 1 µM) maintains S1PR1 protein expression, enhances the human pulmonary artery endothelial cells barrier via S1PR1, but shows no effect on inducing ubiquitination of S1PR1. FTY720 (S)-Phosphate (0.01-50 µM) also reduces β-arrestin recruitment to S1PR1.