Figure 2.

Schematic illustration of corneal epithelial cell differentiation from ESCs or iPSCs. Cultured human iPSCs treated with competitors of BMP, Activin, and Nodal pathways that result in the inhibition of Smad signaling become neuroectodermal progenitors due to activation of earlier neuronal genes (i.e., Zic and Fox family members). In contrast, OVOL2, repressed mesenchymal genes, together with PAX6 and Klf4, activate corneal epithelium differentiation. BMP, bone morphogenetic proteins; OVOL2, ovo-like zinc finger 2; Pax6, paired box protein Pax-6; Klf4, Kruppel-like factor 4; Zic, zinc finger; Fox, forkhead/winged-helix.