Fig. 6. Rac inhibition blocks cyclin D1 expression. (A,B) MCF10A cells were infected with adenoviruses encoding GFP, β-galactosidase (LacZ), N17-Rac, or β2-chimerin and serum starved. Control viruses were used at the highest MOI of the test virus. The infected, serum-starved cells were plated on collagen-coated dishes, stimulated with 10% FBS and growth factors for 9 hours. Collected cells were analyzed by western blotting with the antibodies shown. (C) MCF10A cells were transfected with irrelevant control or Rac1 siRNAs and serum starved. The cells were plated on collagen-coated dishes, stimulated with 10% FBS and growth factor cocktail for the times shown, and analyzed by western blotting using antibodies to cyclin D1, dually phosphorylated ERK, total ERK, Rac and GAPDH (loading control).