IGF1 and retinopathy of prematurity: Retinal stem cells (RSCs) co-cultured with oxygen-induced retinopathy of prematurity (OIR-ROP) retinal tissues could be induced to differentiate into cells expressing β-tubulin and protein kinase C (PKC) and promote the expression of angiogenin-1 (Ang-1) and insulin-like growth factor-1 (IGF-1), thus enhancing proliferation and angiogenesis 26.