Normal Rat Serum (NRS) is the component of blood that does not contain erythrocytes or leukocytes nor clotting factors. All other non-clotting proteins remain in the serum making it a useful reagent for blocking of blots or wells. Normal Rat Serum is non-sterile and not ammenable to cell culture.Synonyms: Rat sera, non-sterile rat serum, normal sera