 Few endogenous regulators have been found to elicit this important regulatory function, such as SOCS1 and Aryl Hydrocarbon Receptor Interacting Protein (AIP).Avian type I IFNs have been characterized and preliminarily assigned to subtypes (IFN I, IFN II, and IFN III), but their classification into subtypes should await a more extensive characterization of avian genomes.Functional lizard type I IFNs can be found in lizard genome databases.