FIG. 4.

Expression of RA-Fgf/Erk signaling during early neural differentiation Schematic diagram of RA-Fgf/Erk signaling in early neural differentiation (A). The screening of the RNA expression of Fgf4 and Fgf8 by qRT-PCR showed that the expression of Fgf4 was readily decreased during the differentiation process and the expression of Fgf8 was increased (as a surge) at day 1 after RA treatment (B). Western blot analysis revealed that phosphor-Erk1/2 was upregulated after RA treatment, and then downregulated in differentiating ESCs and iPSCs (C). Using the ImageJ software to quantify protein expression, we showed that the ratio of phosphor-Erk1/2 intensity to total Erk1/2 intensity was increased to a greater extent in ESCs compared with iPSCs at days 1, 2, and 4 after RA treatment (D). Error bars represent the mean±SEM. (*) P<0.05.