EPO and systemic lupus erythematosus: SLE-associated genes also regulate immune response processes of cell adhesion and migration, regulation of blood vessels (including leukocyte adhesion to endothelial cell and leukocyte transendothelial migration; regulation of blood vessel endothelial cell migration; integrin pathways; platelet-mediated interactions with vascular and circulating cells; VEGFR signaling; angiopoietin receptor signaling; and erythropoietin signaling).