ISG20 and Buschke-Ollendorff syndrome: Our results showed differential gene expression interferon-stimulated gene 20 (ISG20) in both BOS and RAS, while expression of CXCL9 (also referred to as monokine induced by gamma interferon, MIG) and CXCL10 (also referred to as interferon gamma-induced protein 10, IP-10) was only upregulated in RAS tissue.