Figure 4. Microtubule behaviour and stability in patients’ fibroblasts after various periods of cold treatment.

(a) Before cold treatment, the cytoskeleton morphologies were similar among control and mutant fibroblasts (A–C). Note that fibroblasts of R64W and C25F were depolymerised after 15 min of cold treatment, whereas polymerised microtubules were still present in control fibroblasts (J–L). Scale bar, 20 μm. (b) Percentage of completely depolymerised cells after cold treatment of 0, 5, 10, 15, and 20 min. We counted completely depolymerised cells among 275–400 cells in each condition. After 10 min of cold treatment, the percentage of R64W and C25F fibroblasts showing depolymerisation was more than four times that of control fibroblasts. Asterisks indicate statistically significant differences compared with control (Fisher’s exact test and Bonferroni correction using numbers of cells with and without complete depolymerisation, *p < 0.05, **p < 0.0001).