RTN4 and retinopathy of prematurity: Nogo-A, an important member of the reticulon protein family (RTN4), which includes Nogo-B and C, is traditionally associated with the development of the central nervous system [15], which acts as an anti-angiogenic and repulsive factor on endothelium [16] and participates in retinal vascularization, as seen in the OIR model of ROP [16,17].