ANPEP and cancer: In vitro and in vivo CRISPR screenings have identified crucial participants in APM deficiency such as the inhibitory molecule of IFN‐γ signalling PTPN2 and methylation writer of genes involved in MHC‐I antigen presentation pathway polycomb repressive complex 2 (PRC2), providing latent cancer immunotherapy targets as well as emphasising the regulatory complexity of APM.55