Figure 6. Gene expression in E13.5 and E17.5 RPCs under conditions of proliferation and differentiation culture. At 0 d: freshly harvested RPCs; 0–4 d: proliferation culture; 4–12 d: differentiation culture. (The detailed experimental procedure is shown in Figure 5.) GAPDH, a housekeeping gene, served as an internal control. The insert in panel B was the local magnification at 12 days. Note the deviation bars at some points were almost indiscernible due to the large scale of the y-axis. The values were mean±standard deviation from three experiments. The symbols * and ** represent p<0.05 and p<0.01, respectively, versus E17.5 RPCs (A-D) or E13.5 RPCs (E-F). The significance was determined by the Student t-test.