Figure 2 Inducible expression of reporter gene using E2 or 4-OHT. Growth responses of CHO/GEV_GFP cells upon the addition of E2 (A) or 4-OHT (D) . Symbols are indicated as follows. (A) Gray squares, no addition; closed squares, 1.25 µM; closed triangles, 2.5 µM; closed circles, 5 µM; closed diamonds, 10 µM; open circles, 20 µM.(D) Gray squares, no addition; closed squares, 0.01 µM; closed triangles, 0.05 µM; closed circles, 0.1 µM; closed diamonds, 0.5 µM; open circles, 1 µM. Percentage of GFP-positive cells at each concentration of E2 (B) or 4-OHT (E) . Open columns, day 1; light gray columns, day 2; dark gray columns, day 3; closed columns, day 4. Mean green fluorescence intensity at each concentration of E2 (C) or 4-OHT (F) . The distinction of columns is the same as (B) and (E) .