S1PR1 and systemic lupus erythematosus: In the patients with SLE and MRL/MpJ-Faslpr/J (MRL/lpr) lupus-prone mice, several identified miRNAs affect the central pathway of SLE (3); for instance, upregulated miR-21 regulates lymphocyte signaling (4) and miR-155 deficiency which suppresses lupus activity by targeting sphingosine 1-phosphate (S1P) receptor 1 (S1pr1) (5).