S1PR1 and atherosclerosis: To test the role of S1PR1 in myeloid cells in atherosclerosis development, we transplanted BM from either S1pr1MKO or control S1pr1MWT mice into lethally irradiated Ldlr KO recipient mice (hereafter referred as LdlrBM S1pr1 MKO and LdlrBM S1pr1 MWT mice).