AP-1 consists of Fos (c-Fos, FosB, FosL1, FosL2) and Jun (c-Jun, JunB, JunD) proteins, which form dimers that regulate transcription of inflammatory genes relevant to asthma, such as c-Fos and interleukin (IL)-5, and Fra2 and IL-13 (64–66). This evidence concerns the gene JUNB and asthma.