ANGPT4 and retinal degeneration: In hyperoxia, which in short-term promotes astrocyte differentiation (Duan et al., 2017), in long-term causes retinal degeneration (Yamada et al., 1999) and paradoxically can cause hypoxia by blocking vascular development in the retina (West et al., 2005), Angpt1 mRNA expression was decreased while Angpt2 and Angpt4 mRNA levels increased.