Figure 2. Proteasome inhibition upregulates cytoplasmic, endoplasmic reticulum, and mitochondrial chaperones. Lens epithelial cells were treated with or without 10 µM MG132 for 6 h. Total RNA was extracted, and the level of mRNA for these chaperones was determined by real-time RT–PCR using GAPDH a reference. The level of mRNA for these chaperones in the cells not treated with MG132 (the control) was arbitrarily designated as 1. The levels of mRNAs for these chaperones in MG132-treated cells were normalized with the control and expressed as relative levels. Panel A shows the expression of cytoplasmic chaperones. Panel B shows the expression of ER chaperones, an ER stress-related factor, and a mitochondrial chaperone.