Figure 4.

ER requires c-Jun to mediate cyclin D1 promoter activation. HeLa cells were transfected as described in Fig. 2B with: (A) D1–96 Luc together with expression vectors for ER, c-Jun, c-Fos, and ATF-2 alone or in combinations as indicated. (B) D1–96 Luc and ER and/or TAM 67. After 24 h, cells were incubated with 10 nM estradiol for 24 h. At the end of incubation cells were harvested and luciferase activities were measured and normalized to β-galactosidase activities. F, c-Fos; J, c-Jun; A, ATF-2. C. In vitro interaction of c-Jun and ATF-2 with ER. ³⁵S-labeled c-Jun and ATF-2 were prepared by translation in vitro. Labeled protein probes were incubated with immobilized GST or GST-ER mutants. Equal amounts of ³⁵S-labeled proteins were incubated with each resin. After extensive washing of the GST beads, the proteins were eluted, separated on PAGE, and detected by fluorography. The input lanes contained 10% of the labeled proteins.