FIGURE 2.

Deficient APM promoter activity in HER-2/neu⁺ cells correlated with reduced RNA pol II-initiated transcription in HER-2/neu⁺ cells. A, WT APM-luc promoters or APM-mut-luc promoters and the pGL3/Enhancer vector, which served as a control (data not shown), were transiently cotransfected with the β-gal vector into HER-2/neu⁻ and HER-2/neu⁺ cells 48 h prior to the determination of the luc activity using a reporter gene assay as described under “Experimental Procedures.” The data were normalized to β-gal activity. For comparison, the WT APM promoter activities in HER-2/neu⁻ cells were set to 100%, and the respective APM promoter activities in HER-2/neu⁺ cells were calculated. Error bars indicate S.D. rel luc activity, relative luc activity. B, immunoprecipitated chromatin of HER-2/neu⁻ and HER-2/neu⁺ cells was used as template in PCR. Dilutions (1:10) of input DNA served as controls. Sequences of the APM promoters (TAP1, LMP2, TAP2, and tapasin) and the EF-1α promoter were amplified from RNA pol II-ChIP of HER-2/neu⁻ cells and from HER-2/neu⁺ cells, but not from isotype control IgG-ChIP. A non-template control was included.