Produced by macrophages, IFN-alpha have antiviral activities. Interacts with IFNAR2. Three alleles exist; alpha-2A, alpha-2B (shown here) and alpha-2C (PubMed:7627809). Allele alpha-2B is the predominant allele while allele alpha-2A is less predominant and alpha-2C only a minor allelic variant. Available under the names Roferon-A (Roche) or Intron-A (Schering-Plough). Used as an anticancer drug for its antiproliferative activity. Belongs to the alpha/beta interferon family.