Figure 2.

Network of transcription factors that establish the eye field. The neural ectoderm transcription factors SOX2 and OTX2 activate Rax expression in the prospective eye field, which is located in the ventral forebrain. RAX is required for the up-regulation of the EFTFs Lhx2, Pax6, and Six3 in the eye field. The dashed arrows indicate that LHX2 may coregulate the expression of Rax, Pax6, and Six3 in the eye field, as expression of these genes is delayed in Lhx2^−/− embryos (Tetreault et al. 2009). The EFTFs then coordinate the cell-intrinsic and -extrinsic signaling pathways that regionalize the optic vesicle along its axes.