On the one hand it has been suggested that OPN has neuroprotective and repair-promoting effects in neurodegenerative diseases such as Alzheimer’s disease and considering the parallels between AMD and neurodegenerative diseases, it is possible that OPN might be induced and secreted from RPE cells in a last-ditch effort to preserve its function99–101. The gene discussed is SPP1; the disease is age-related macular degeneration.