Figure 4. Disruption of endoplasmic reticulum function in lens epithelial cells upregulates Hsp40 and many endoplasmic reticulum chaperones. Lens epithelial cells were treated with or without 5 µg/ml tunicamycin for 6 h. Total RNA was extracted, and levels of mRNA for these chaperones were determined by real-time RT–PCR using GAPDH as a reference. The level of mRNA for these chaperones in cells not treated with tunicamycin (control) was arbitrarily designated as 1, and the level of mRNA for these chaperones in tunicamycin-treated cells was 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.