PTTG1 and Drug-Induced Senescence Figure 6. Xenografted PTTG12/2 tumors are more sensitive to doxorubicin (Dox). a) HCT116 WT and PTTG12/2 HCT116 cells were implanted subcutaneously into nude mice and treated with control vehicle (C) or doxorubicin. Tumor dimensions were measured twice a week; b) twenty one days after tumor cell xenografts, mice were sacrificed, tumors separated and weighed; c) harvested tumor tissues were sectioned and stained with b-gal; d) tumor tissue was stained for p21 immunoreactivity; e) harvested tumor tissues were homogenized and Western blot performed. Results are expressed as mean6SD, n = 10, *p,0.05, **p,0.001. doi:10.1371/journal.pone.0023754.g006 PLoS ONE | www.plosone.org 10 August 2011 | Volume 6 | Issue 8 | e23754