JUN and neoplasm: This feature is in line with the notion that C4.4A expression is strictly regulated (Seiter et al, 2001; Smith et al, 2001; Hansen et al, 2004), requires a C/EBPβ/JunD or c-Jun complex for induction of transcription (Fries et al, 2007) and can also be induced in tumour lines by not yet defined heat-labile serum factors (Würfel et al, 2001).