EDN2 and retinal degeneration: We furthermore analyzed mRNA expression levels by qPCR of factors like leukemia inhibitory factor (Lif), fibroblast growth factor 2 (Fgf2), and endothelin 2 (Edn2) that are well-known to be upregulated in the context of retinal degeneration [10,11,12] and found them to be significantly upregulated in retinae of three-month-old VPP mice (Lif: 22.38 ± 4.13, p = 0.008; Fgf2: 13.17 ± 1.52, p = 0.005; Edn2: 46.33 ± 5.64, p < 0.001) compared with retinae of control littermates (Lif: 1.00 ± 0.18; Fgf2: 1.00 ± 0.14; Edn2: 1.00 ± 0.15) (Supplementary Figure S1G).