Among these cell lines was the HLA-I high cell line SHEP, which is derived from a mesenchymal neuroblastoma tumor, a rare subtype with high immunogenicity and high expression of APP proteins, including tapasin (45).The immunopeptidomes from both parental and tapasin-TM–expressing cell lines were captured and used in subsequent analysis (table S2). Here, APP is linked to neuroblastoma.