Figure 3.

ATF-2 and a CREB/CREM protein bind to the cyclin D1 CRE in chondrocytes. Nuclear extracts from MCT cells were incubated with ³²P-labeled double-stranded oligonucleotides corresponding to the cyclin D1 CRE sequence. The resulting complexes (lane 1) could be blocked by a 100-fold excess of unlabeled CRE oligonucleotides (lane 2). Incubation of extracts with an unrelated oligonucleotide did not produce a complex (data not shown). Addition of an ATF-2 antibody (lane 4) resulted in slower migration of the upper complex (ss, supershift), whereas incubation with a CREB/CREM antiserum (lane 5) reduced the abundance of both complexes. Addition of control IgG (lane 3) or antibodies (Ab) against c-Fos (lane 6) or different Jun proteins (lanes 7 and 8) did not affect the formation or migration of the complexes.