IFNA1 and myeloid sarcoma: IFNß1b (Betaferon®, Betaseron®) was the first MS disease-modifying agent.[1–3] IFNß1b has three molecular differences from human IFNß: it is not glycosylated [since it is made in bacteria (Escherichia coli)], is missing the N terminal methionine, and has a serine for cysteine substitution at position 17.