Expression of the Ap-1 (Jun) factor and EMSA analysis with nuclear extract from CHO-K1 cells. A) Ap-1 mRNA was detected in CHO cells and monkey placenta by RT-PCR. B) Ap-1 protein was analyzed in the total, nuclear, and cytoplasmic proteins extracted from CHO cells by western blot. C) EMSA was performed for the wild-type (-288-Luc) and nucleotide-converted mutants (mut-1, mut-2, mut-3) with nuclear extract (3 μg) from CHO cells using 20 fmol of biotin-labeled double-stranded oligonucleotide probe. The protein-DNA complex was transferred to a Zeta probe membrane. Detection of biotin-labeled DNA was performed using the LightShift chemiluminescent EMSA kit and exposed to X-ray film.