PTTG1 and Drug-Induced Senescence Figure 5. Protein levels on p21 promoter after drug treatment. a) WT and PTTG12/2 cells were treated with control vehicle (C), 0.02 uM doxorubicin (Dox) or 0.005 uM TSA for 48 hours. Cells were harvested and chromatin immunoprecipitations performed using the indicated antibodies. Enriched chromatins were evaluated using qPCR and primer pair 1. Levels of p21 promoter binding were normalized to these of WT control HCT116 cells after doxorubicin or TSA treatment and are depicted as a) histone H3 acetylation; b) histone H4 acetylation; c) P300 binding; d) HDAC1 binding; e) PTTG12/2 or p532/2 cells were transfected with scramble (C) or p300 siRNA, and p21 promoter containing or devoid of the p53 binding site. Results are expressed as mean6SD, n = 3, *p,0.05, **p,0.001. doi:10.1371/journal.pone.0023754.g005 PLoS ONE | www.plosone.org 9 August 2011 | Volume 6 | Issue 8 | e23754