Accumulation of unfolded, misfolded, or damaged proteins is deleterious to cells. To avoid such potentially harmful conditions, cells have evolved efficient protein quality control systems (PQC). One of the key effectors of this PQC is the ubiquitin–proteasome system. In this system, ubiquitin-tagged proteins are recognized by the 26S proteasome for proteolytic destruction. Increasing evidences link 26S proteasome deficiency to various human diseases, most prominently cancer and neurodegenerative disorders. Thus, preventing the decrease of proteasomal activity observed during ageing and/or reversing proteasomal defect in pathologies has a huge therapeutic potential. In this talk, I will introduce some of my work on the discovery of an evolutionarily conserved homeostatic response that increases proteasome assembly in order to maintain proteasomal degradation and cell viability under stressful conditions. The master regulators of growth and stress TORC1 and Mpk1/Erk5 are central to this response; with Mpk1/Erk5 coordinating the upregulation of 19S regulatory particle assembly chaperones (RACs) and proteasome subunits following TORC1 inhibition.