a, Rousseau and Bertolotti2 report that activation of the yeast mitogen-activated protein kinase enzyme (MAPK) known as Mpk1 mediates an increase in the levels of regulatory particle assembly chaperone proteins (RACs) and subunits required for the formation of the proteasome complexes that mediate protein degradation. Mpk1 is activated by inhibition of TORC1 protein kinase activity. TORC1 can be inhibited by tunicamycin or rapamycin treatment or by the action of the protein Sfp1. b, The authors also show that this process of proteasomal regulation is conserved in mammals — ERK5, the mammalian protein kinase most similar to Mpk1, is required to upregulate mammalian proteasome levels through an increase in RACs and proteasome subunits upon mTORC1 inhibition by compounds such as rapamycin or by nutrient starvation. In both yeast and mammals, an increase in proteasome abundance is necessary for cell survival under stress.