The PSMB9 gene encodes one of the catalytic subunits of the i-proteasome, which replaces the standard catalytic subunit in the 20S core during proteasome assembly; PSMB9 engages in macromolecular catabolic processes involving proteasomes and may limit antigen processing and presentation, making the PSMB9 gene an attractive candidate gene for raising cancer risk [15]. This evidence concerns the gene PSMB9 and cancer.