PSMB9 and thymic epithelial neoplasm: To evaluate the relevance of the UPS in TH and TC, we analyzed the expression of the proteasomal subunits β5c (PSMB5), β2c (PSMB7), β5i (PSMB8), β1i (PSMB9), β2i (PSMB10), β5t (PSMB11), UBA1, and NEDD8 by immunohistochemistry on tissue microarrays of 138 TET samples (Tables 1 and S4).