They were able to induce peripheral blood lymphopenia as a characteristic of successful downregulation of the S1P1 and, in the case of [(S)-PO3H2]-49, a robust time-dependent phosphorylation of MAPK was observed, indicating its ability to interact with and activate the S1PR1 and S1PR3 receptors [218]. This evidence concerns the gene S1PR1 and lymphopenia.