Sensitivity of rpn3 mutants to drugs that cause protein damage is suppressed by Rpn3. RPN3, rpn3-4, rpn3-7, and the mutants expressing high-copy Rpn3 were spotted on agar medium and incubated at either 23 °C or 37 °C (two left panels). Serial dilutions (10-fold) of the same cultures were also spotted on medium containing paromomycin, hygromycin B, and canavanine. Growth was examined after 3–5 days. Drug sensitivity was examined at 23 °C in medium containing 100 μM CuSO4 to induce expression of Rpn3.