FIG. 1.

(A) Changes of AP-1 complexes I and II detected in nuclear extracts of REF, E1A-immortalized, E1A + E1B19kD, and E1A + cHa-ras cells with the coll-TRE or jun2-TRE probes in electrophoretic mobility shift assays (EMSA). Nuclear extracts were prepared from cells grown in medium supplemented with 10% FCS. The positions of the slower migrating complex (I) and the faster complex (II) have been indicated. (B, C) Regulation of AP-1 DNA binding activity in REF cells (B) and E1A + cHa-ras transformants (C). Cells were serum starved in the presence of 0.5% FCS for 48 h and stimulated by addition of 10% FCS, EGF, TPA, or dbcAMP for 1 h (see Materials and Methods). Nuclear extracts were isolated and used in EMSA. The labeled coll-TRE oligonucleotide was used as a probe.