Effects of GF on the microtubules of MCF-7 cells. MCF-7 cells were incubated without or with different concentrations of GF for 48 h. (A) Microtubules (red) and chromosomes (blue) of interphase cells or (B) Microtubules (red) of metaphase cells are shown. Arrows point towards the poles. Bar equals to 20 and 10 μm for an interphase and a metaphase cell, respectively. (C) Effects of GF on the polymer mass of tubulin in MCF-7 cells. (D) Band intensities of the polymeric and soluble tubulin fractions in MCF-7 cells treated with different GF concentrations relative to the vehicle-treated cells are shown. The experiment was performed three times. Data represent mean ± SD.