fig5

Figure 5. PA16.gemR tumors maintained gemcitabine resistant phenotype in the absence of exposure to gemcitabine. Average tumor volumes ± S.E.M. of PA16.gemR tumors in mice treated with gemcitabine 100 mg/kg weekly or with saline control for 5 weeks. Tumor volumes are normalized to day 0 of treatment (A); photomicrographs of PA16.gemR tumors harvested three days after the completion of therapy were stained for H&E and immunostained for the proliferation marker Ki67. Scale bar = 10 μm (B); Ki67 IHC data in B were quantitated as described in Methods to determine proliferation indices. Ki67 proliferation indices were compared by Student’s t-test. NS: not significant (C). gemR: gemcitabine resistance; IHC: immunohistochemistry