[21] Carboxyethylpyrrole (CEP) modified proteins, found in drusen, are one such example of a danger signal. They are present in increased amounts in eyes with AMD and have been shown to be able to prime certain PRRs, known as NLRP3 (part of the intracellular NOD-like receptor family). [22] NLRP3 has also been linked to the formation of geographic atrophy, one of the hallmarks of dry AMD. [23]. This evidence concerns the gene NLRP3 and age-related macular degeneration.