In contrast, deletion or inhibition of proteasome catalytic subunits (Psmb9, Psmb10 or Psmb5) and activators (PA28) are associated with exacerbation of cardiac I/R injury and cardiomyopathy [14, 15, 17, 18], suggesting that these factors could be novel targets for therapeutic intervention in hypertrophic or ischaemic heart diseases. Here, PSMB5 is linked to cardiomyopathy.