1. From the Baxter Laboratory in Stem Cell Biology, Stanford University, Stanford, California (G.K.F., B.G., N.A., G.P.N.); Department of Microbiology and Immunology, Stanford University, Stanford, California (G.K.F., G.P.N.); and Department of Anesthesiology, Perioperative, and Pain Medicine, Stanford University School of Medicine, Stanford, California (B.G., E.A.G., M.T., M.S.A.).