Purity >90%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie? Blue Staining. MW (observed): 17 kDa, reducing conditions. MW (theoretical): 18 kDa. The Recombinant Mouse IL-18/IL-1F4 Protein from R&D Systems is derived from E. coli. The Recombinant Mouse IL-18/IL-1F4 Protein has been validated for the following applications: Bioactivity.