FIGURE 2. Wild-type and racE null cells form a contractile ring rich in myosin II when attached to a substrate. Both cell types were transfected with an expression vector for the production of GFP-myosin II heavy chain. Adherent cells were fixed and stained with DAPI to visualize their nuclei. (A-C) Dividing wild-type cells have a characteristic dumbbell shape and compact nuclei. In these cells, GFP-myosin II is highly concentrated in the contractile ring. (D-I) When racE null cells divide on a substrate, they also have a normal dumbbell shape, with compact nuclei and a myosin II contractile ring.