The effect of βIVa-tubulin silencing on pancreatic cancer cell clonogenic cell growth and chemosensitivity. Bars represent the number of MiaPaCa-2, HAPF-II or AsPC1 cell colonies (mean + S.E.M. as a % of mock treatment) that formed from low density seeding following transfection with control siRNA (ns-siRNA), or βIVa-tubulin siRNA (βIVa-Tub siRNA) and 72 h culture in titrations of Gemcitabine (A-C), Taxol (D-F) or Vincristine (G-F). Asterisks indicate significance relative to the 0 nM control for the same siRNA. Hashes indicate significance relative to the ns-siRNA control of the same drug dose (* or #P ≤ .05, **P ≤ .01, ***P ≤ .001, ****P ≤ .0001; n ≥ 4).