FIGURE 6.

ChIP assay in T47D cells to assess recruitment of transcription factors to the rexinoid-responsive fragment of the IGFBP-6 gene after 12 h of bexarotene treatment. A, design of the PCR assay encompassing the bexarotene-responsive element in intron 1 of IGFBP-6. B, PCR amplification of the DNA segment 2524–2697 following chromatin immunoprecipitation with antibodies against RXRα, RXRβ, RARα, RARγ, cJun, cFos, ATF2, and p300. Normal rabbit IgG was used as negative control. C, determination of immunoprecipitated chromatin upon bexarotene treatment using quantitative real time PCR. Samples were normalized to their respective input, and values are expressed relative to vehicle-treated counterparts. D, binding of RXRα in the presence or absence of RARβ or cJun to the IGFBP-6 gene. Chromatin IP detecting recruitment of RXRα and cJun to the bexarotene-responsive site of IGFBP-6 in controls (si NS) and cells after depletion of RARβ or cJun (siRARβ, si cJun).