To test whether β5i/LMP7 deficiency was indeed sufficient to negatively affect the incorporation of all three inducible catalytic subunits into cardiac IP in vivo, heart 20S proteasomes were isolated from naive mice and from CVB3-infected mice at the early stage of disease (d4 p.i.)and at the acute stage of myocarditis (d8 p.i.)from both β5i/LMP7+/+ and β5i/LMP7-/- mice. The gene discussed is PSMB8; the disease is myocarditis.