PROM1 and infection: To verify the infection of AAV-Igf1, we performed a western blot analysis on the Prom1+/−  retina infected with AAVs conveying Gfp (control) or Igf1. We found that pS6 was upregulated by AAV-Igf1, but not by AAV-Gfp, at 2 weeks post infection, confirming that AAV-Igf1 properly activated IGF signalling (Fig. 4C).