Figure 6

Role of RhoA and Rac1 in serum deprivation-dependent rearrangement of the actin cytoskeleton and cell shape. To examine the role of RhoA and Rac1 in serum deprivation-induced reorganization of the actin cytoskeleton underlying motility and invasive ability, MDA-MB-435 cell monolayers were (a) left in fresh whole growth medium (nondeprived) or were serum deprived (deprived) for 1 day after transfection with empty pBabe vector (Cont) or with dominant negative (dn)-N19RhoA, constitutively active (ca)-V14RhoA, dn-Rac1 or V12Rac1 inserted in the same vector (bar = 10 μm). Arrows indicate the presence of lamellipodia whereas pseudopodia are indicated by arrowheads and invadopodia along the cell surface or at the end of an dominant leading edge pseudopodia are indicated by an asterist. (b) The complex actin organization of a long, dominant leading edge pseudopodia extension in a cell transfected with dn-RhoA and deprived of serum at a higher magnification (bar = 5 μm).