ANPEP and cancer: A recent CRISPR screen aimed at identifying genes responsible for low MHC-I expression in cancer cells identified the evolutionarily conserved polycomb repressive complex 2 (PRC2), which is known to modulate gene expression during embryonic development via histone methylation, and causes repressive histone methylation not only at MHC-I and APM gene promoters but also at the NLRC5 promoter [180].