As metabolic similarities exist between PRs and cancer cells (Du et al., 2013b; Ng et al., 2015), and the Gls cKO mouse retina demonstrated ISR activation and apoptosis (Figures 1G-I and 6C-D), decreased protein synthesis (Figure 6E), and decreased Asp (Figure 6A), Asn supplementation was explored and proved effective as observed in the rescue of PR degeneration in the cKO mouse (Figure 6H). The gene discussed is GLS; the disease is cancer.