Fig. 6. GST-LIM2-LIM3 inhibits microtubule catastrophe at focal adhesions. (A,B) Cell expressing GFP–β-tubulin (green) and mRFP-zyxin (red) before (A) and after (B) microinjection of GST-LIM2-LIM3 protein. After injection, the microtubule density increases as a result of catastrophe suppression at adhesion sites. Bar 10 µm. (C,D) Kymographs of microtubule dynamics at focal adhesions. A microtubule undergoes catastrophe at an adhesion before injection (C) but grows through adhesions after injection (D, arrows). (E,F) Examples of microtubule life-history plots in cells before (E) and 30 minutes after (F) injecting the GST-LIM2-LIM3 construct. The black line indicates the tracking position of individual microtubule tips in relation to focal adhesions (FA) marked with red, green and yellow lines. Note multiple catastrophes at adhesions in (E), whereas microtubules grow through several adhesions without catastrophe in (F). (G) Frequency of catastrophes per square micron before and after microinjection of GST-LIM2-LIM3 protein. Upon injection, the frequency of catastrophes reduces in focal adhesions (upper bracket) but stays the same in the cytoplasm (lower bracket). Data are shown for 271 catastrophes in five individual cells recorded both before injection and 30 minutes after injection. (H) The difference in microtubule catastrophe before (blue boxes) and after (red boxes) injection of GST-LIM2-LIM3 shown in a `box-and-whisker' plot. The P value was calculated by a t test (Microsoft Excel). The reduced frequency of catastrophes at focal adhesions after injection of GST-LIM2-LIM3 was statistically significant (P<0.001). At the same time, the frequency of catastrophes in the cytoplasm did not change (P=0.24).