PSMB8 and head and neck squamous cell carcinoma: To determine whether thymic carcinomas are particularly amenable to carfilzomib treatment compared to similar tumors from other organs, we analyzed the expression of the CPS subunit β5 (PSMB5) and the IPS subunit β5i (PSMB8) in tissue samples of n = 10 TC and n = 5 lung squamous cell carcinomas (LSCC) and n = 5 head and neck squamous cell carcinomas (HNSCC) by immunohistochemistry (Fig. 5A-C) and western blotting (Fig. 5D and E).