MTCBP-1 overexpression significantly reduces metastasis of pancreatic cancer cells. (A and C) Images of the small bowel of nude mice 18–20 d (DanG, A) or 8 wk (BxPC3, C) following orthotopic pancreatic injection of stable cell lines expressing either FLAG control or MTCBP-1-FLAG. The mice injected with control tumor cells formed a significant number of metastatic lesions (arrows) whereas metastasis was significantly reduced in the mice injected with MTCBP-1-FLAG–expressing tumor cells (A and C). (B and D) The number of macroscopic metastases and the primary tumor weight were scored upon necropsy. Graphs represent data from two independent experiments; lines represent averages ± SEM. *, P < 0.05; ***, P < 0.0005; ns, not significant. (E and F) Western blot demonstrating expression of MTCBP-1 and MT1-MMP in primary and metastatic tumors collected from mice that were orthotopically injected with virally transduced DanG cells (E) or BxPC3 cells (F). Note the decreased endogenous and ectopically expressed MTCBP-1 protein levels in metastases from mice #1, #2, #3, and #4 comparing to the corresponding primary tumor. Numbers at top of gel lanes (#1–4) represent individual mice. All blot measurements in kD.