APP and cancer: In a recent study, the genome‐wide CRISPR screen was applied in K562 tumor cells (known for their low MHC‐I expression) and cancer cell lines in which an evolutionarily conserved polycomb repressive complex 2 (PRC2) protein was identified and implicated in the transcriptional regulation of MHC‐I antigen processing pathway (MHC‐I APP), which highlights the tight epigenetic control of MHC‐I expression in these tumor cells.