Fig. 8. Overexpression of MUK modifies microtubule organization. (A) COS-1 cells were transfected with expression vectors for GFP (a,b), T7-MUK (c,d), and T7-MUK/KR (e,f). Fixed cells were double-stained using anti-T7 antibody (c,e) (green) and anti--tubulin antibody (b,d,f) (red). The expression of GFP was detected by its fluorescence (a). Arrows in c and d indicate T7-MUK-expressing cells losing the radial array of microtubules. Arrowheads indicate the radial array of microtubules observed in GFP- or T7-MUK/KR-expressing cells and cells without detectable levels of T7-MUK expression. Scale bar: 50 µm. (B) The frequency of radial array appearance was analyzed statistically. Small panels shows the definition of radial array +, ± or – cells. The appearance of the radial array is expressed as percent of the GFP-, T7-MUK-, or T7-MUK/KR-positive cells counted (n>300) (*P<0.005 versus GFP or MUK/KR control). Error bars represent the standard deviation of three independent transfection experiments.