Figure 2. mRNA expression of Oct-4, K3, and p63 with GAPDH as an internal control for P2 in all groups, E₁₄ and P6, P9, P18 of e-Pc. After the mES cell extract treatment, Oct-4 mRNA was detected in P2 (day 12), reached its peak at P9 (week 4), and decreased in later passages. It remained undetectable in the two control groups. Expression of corneal tissue-specific marker K3 mRNA increased as passage in experiment group, and progenitor cell marker p63 was also found in these cells.