JUN and neoplasm: Fra-2 (Fos-related antigen-2) is part of the AP-1 (activating protein-1) transcription factor complex, consisting of the Fos-, Jun-, ATF-, and MAF-protein families (Angel and Karin 1991; Eferl and Wagner 2003; Goetz et al. 1996; Vogt and Bos 1990) that bind to regulatory sequences of various target genes, which in turn are induced by growth factors, cytokines, oncoproteins, or tumour promoters like TPA (12-O-tetradecanoylphorbol-13-acetate).