Question

A wound healing assay shows that expression of high GDI levelsproduces defects in cell migration. To assess actin organization inthese cells, you perform immunofluorescence microscopy analysiswith antibodies to actin and an appropriate secondary antibody.This experiment shows that actin organization at the leading edgeof the cell is normal, but that there are significantly fewerstress fibers in the cell body and towards the trailing edge of thecell.

Which of following answer is most consistent with yourobservation?

GDI overexpression reduces the cytosolic concentration ofG-actin ATP so that F-actin is rapidly depolymerized

GDI overexpression stimulates the activity of Rho, which thenbinds to the actin nucleation protein formin to nucleate linearactin filaments

GDI prevents a chemoattractant in the medium to bind to thereceptor so that migration cannot occur

GDI sequesters the small GTPase Rho in the cytosol so that itcannot be activated by its GEF

GDI blocks the activation of Rac at the leading edge of thecell.