Fig. 7. ES cells produce activin-Nodal activities for self-propagation. (A) Luciferase reporter assay of MGZ5 cells with reporter constructs (ARE-luc reporter or Id-1-luc reporter). Control, cells transfected with reporter and control vectors only; Smad7, Smad6, empty, cells transfected with each expression plasmid; SB-431542, DMSO, cells cultured in medium supplemented with SB-431542 or DMSO (as control for SB-431542). Each bar represents the mean ± s.e.m. (n=3). (B) Colony morphologies of MGZ5 cells treated with SB-431542. MGZ5 cells were seeded at 2000 cells/well in six-well plates and cultured in serum-free medium supplemented with 3 µM SB-431542 (right) or DMSO (as control, left) for 1 week. Numbers indicate numbers of colonies appearing (n=3). Bars, 5 mm. (C) Relative numbers of cells treated with SB-431542 or DMSO present on Day 7 of culture compared with that at Day 0. Each bar represents the mean ± s.e.m. (n=3). (D) Relative proliferation intensity is shown as total cell number/number of colonies appearing, compared with that in cells treated with DMSO (100%). Each bar represents the mean ± s.e.m. (n=3).