A regulatory element that mediates co-operation between a PEA3-AP-1 element and an AP-1 site is required for phorbol ester induction of urokinase enhancer activity in HepG2 hepatoma cells. - Nerlov, C; De Cesare, D; Pergola, F; Caracciolo, A; Blasi, F; Johnsen, M; Verde, P (EMBO J, 1992)