TAPBP and glioblastoma: Furthermore, 49 (10.6%) tumors had LOH affecting APP gene(s) in the HLA region (TAP1/2, TAPBP, PSMB8/9, HSPA1A-L), including 14 (20.6%) osteosarcoma and five (22.7%) GBM cases with LOH in both TAP1 and TAP2.