Disclosed is a protein exhibiting human interferon-like anti-viral and anti-proliferative biological activities, wherein said protein is selected from the group consisting of proteins each comprising an amino acid sequence at least 89% identical to SEQ ID NO: 2. Also disclosed is the use of a protein comprising an amino acid sequence at least 89% identical to SEQ ID NO:2 and exhibiting anti-proliferative biological activity, in the manufacture of a medicament for treating cancer responsive to interferon alpha therapy in a subject in need thereof.