Brg-1 and Sp1 are components of the same nuclear complexes. (A) Nuclear extracts from 4T1, 168FARN and 67NR cells were immunoprecipitated (IP) using Brg-1 antibodies or rabbit IgG (control). The immunoprecipitates were subjected to SDS/PAGE gel followed by Western blot analysis using antibodies against Sp1 and Brg-1. (B) The co-immunoprecipitation assay was carried out by using Sp1 antibody or rabbit IgG for the IP and Brg-1 or SP1 antibodies for the Western blot analysis. (C) 4T1, 168FARN and 67NR cells were cross-linked and subjected to sonication and immunoprecipitation with the indicated antibodies. ChIP was first carried out using the Sp1 antibody, and the immunocomplexes were eluted using 10 mM dithiothreitol. The aliquots of the diluted elution were immunoprecipitated with Brg-1, or non- specific IgG as a control. The precipitated DNA fragments were amplified by PCR using the primers specific to the SPARC promoter region containing GGAGG repeats (spanning nucleotides -201/-23). The illustrated results are representative of three independent experiments.