ERAP1 and neoplasm: Each cohort conserves only one of two ERAP genes, which modify peptides for presentation by MHC class I. Clearly, the ERAP function is critical for optimal fitness in each cohort, and we note ERAP1/2 expression was detected in all 9,125 tumor specimens in The Cancer Genome Atlas database (TCGA), and deep deletions are rare (0.6–0.8%) (Compagnone et al., 2019.