ChIP analysis showing the interaction of ATF4 with the Mcl-1 promoter. (A) Human Mcl-1 upstream region showing 3 consensus sites for ATF4. There is only 1 consensus site for ATF4 at the promoter of murine Mcl-1. The core consensus motifs are boxed. (B) ChIP analysis of ATF4 binding in bortezomib-treated LP1 cells. LP1 cells were treated with 100nM bortezomib for 16 hours. Immunoprecipitation was performed using control IgG or anti-ATF4 Ab. Samples were analyzed by qRT-PCR using primers for region −1521 to −1297, −1033 to −733, and −423 to −80 nucleotides. *P < .05 versus control IgG-immunoprecipitated samples (n = 3).