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Figure 2. PA18 CDC25B-high tumors are sensitive to JQ1, but less sensitive to gemcitabine. JQ1 inhibits CDC25B expression. (A and B) Tumor growth inhibition in mice treated with JQ1 50 mg/kg daily for 3 weeks for PA16 (A) or PA18 (B) PDX tumors. Tumor volumes at the termination of treatment are shown in the right panels as bar graphs. N = 8 tumors/group for PA16; N = 7 for control and N = 9 tumors for JQ1 for PA18. Initial average tumor volumes (mm³) for PA16 were 174 (Control) and 214 (JQ1), and for PA18 were 546 (Control) and 446 (JQ1); (C and D) Tumor growth inhibition in mice treated with gemcitabine 100 mg/kg weekly for 5 weeks for PA16 (C) or P18 (D) PDX tumors. Final tumor volumes (tumor volumes on the last day of treatment) are compared in the right panels as bar graphs. Efficacy data were analyzed by two-way ANOVA followed by Sidak post test or unpaired t test (prism). ^*P < 0.05, ^**P < 0.01, ^***P < 0.001, ^****P < 0.0001. N = 8 for control and N = 7 for gemcitabine for PA16; N = 7 for control and N = 8 for gemcitabine for PA18. Initial average tumor volumes (mm³) for PA16 were 180 (Control) and 240 (gemcitabine), and for PA18 were 175 (Control) and 210 (gemcitabine); (E and F) Tumor tissue harvested from mice treated with control, gemcitabine, or JQ1 was stained with H&E and immunostained for CDC25B, for PA16 (E) or PA18 (F) tumors. Expression indices for CDC25B are shown in the left corner of each photomicrograph. CDC25B: Cell division cycle 25B; PDX: patient-derived xenograft; ANOVA: analysis of variance; H&E: hematoxylin and eosin.