FIGURE 2.

4PBA increases ERp29 protein expression in IB3-1 cells. IB3-1 cells were incubated at 37 °C with 1 mm 4PBA for the indicated times. Equal amounts of whole-cell lysate protein were resolved on 10% SDS-polyacrylamide gels. A, representative immunoblot performed with an ERp29-specific rabbit polyclonal antibody (22). B, densitometric analysis (mean ± S.E.) of 10 independent experiments normalized to zero time. Statistical significance was determined by ANOVA in comparison with the t = 0 sample. C, expression of BiP/grp78 relative to that of GAPDH was determined by densitometry of immunoblots equivalent to those in B (n = 4 independent experiments, all normalized to zero time). Immunoblots were probed with anti-BiP and anti-GAPDH, and each data set was normalized by GAPDH content (mean ± S.E.). By ANOVA, there were no significant differences for GAPDH or BiP/grp78 as a function of 4PBA exposure in these experiments.