FIGURE 8.

BAR protein levels are reduced by prolonged ER stress induced by thapsigargin. A and B, HeLa cells without BI-1-HA induction (A) or induced with 500 ng/ml of doxycycline for 24 h (B) were treated with 1 μm thapsigagin (TG) for various durations as indicated. Levels of endogenous BAR and tubulin were determined by immunoblot analysis of cell lysates (normalized for total protein content) with antibodies to BAR and tubulin. Relative levels of endogenous BAR protein were quantified by scanning densitometry (mean ± S.E.; n = 3). BAR protein levels prior to TG treatment (0 h) were adjusted to 1. C and D, HeLa cells without BI-1-HA induction (C) or induced with 500 ng/ml of doxycycline for 24 h (D) were treated with 1 μm thapsigagin (TG) for various durations as indicated. Total RNA was extracted from cells. RT-PCR analysis of BAR mRNA was performed. RT-PCR for GAPDH served as a control. No significant change in BAR mRNA levels was detected.