As shown in Fig. 5F, nearly all proteasome subunits (e.g., PSMA1, PSMA2, PSMA3, PSMA4, PSMA5, PSMA6, PSMA7, PSMB1, PSMB2, PSMB3, PSMB6, PSMB7, PSMB8, and PSMB9) were considerably upregulated in COVID-19-M patients, compared with COVID-19 patients and HCs. Here, PSMB2 is linked to COVID-19.