Induction of F-actin and microtubule alignment by expression of the formin FH1–FH2 module.

<p>FH1–FH2 containing derivatives of thirteen of the fifteen mammalian formins were over-expressed by transient transfection in HeLa cells and the effects on cellular morphology were observed by immunofluorescence. <b>A</b>) Over-expression of Dia1 FH1–FH2 (left panel) induces stress fiber formation (middle panel) and their concomitant co-alignment with the microtubule network (right panel). <b>B</b>) INF2 FH1–FH2 expression also induces co-alignment of stress fibers and microtubules. <b>C</b>) Over-expression of FHOD1 FH1–FH2 fails to induce stress fiber formation. <b>D</b>) INF1 FH1–FH2 expression induces stress fiber formation and microtubule co-alignment. <b>E</b>) Quantification of stress fiber formation. The number of transfected cells with obvious increased stress fiber formation was counted. N = 3, with greater than 100 cells counted per sample. Error bars represent SEM. <b>F</b>) Summary of stress-fiber alignment with the microtubule network as assessed visually by immunofluorescence.