Fig. 4.
PDGF-stimulated Erk5-mediated mesangial cell proliferation is regulated by cyclin D1. Mesangial cells were transfected with dominant negative Erk5 and cyclin D1 (A and B) or siErk5A and cyclin D1 (C and E) or siErk5B plus cyclin D1 (D and F). PDGF-induced DNA synthesis (A, C, and D) and proliferation (B, E, and F) were determined as described in materials and methods. Bottom: expression of indicated proteins from a parallel experiment. In A, C, and D, means ± SE of triplicate measurements are shown. *P < 0.001 vs. control; **P < 0.001 vs. PDGF-treated; #P < 0.001 vs. control; @P < 0.001 vs. PDGF plus dominant negative Erk5 or PDGF plus siErk5A or siErk5B. In B, E, and F, means ± SE of triplicate measurements are shown. @P < 0.002 vs. control; *P < 0.0002 vs. PDGF alone; #P < 0.01 vs. control; **P < 0.0002 vs. PDGF plus DN Erk5 or PDGF plus siErk5A or PDGF plus siErk5B. For A, a representative of 4 independent experiments is shown. For B–F, representatives of 3 independent experiments are shown.