4-PBA significantly inhibits tunicamycin (TM)-induced CHOP expression.

<p>HK-2 cells were treated with DMSO (VEH), TM (1 µg/ml), 4-PBA alone (1 mM), or TM with 4-PBA for 24 h. Cells were lysed and underwent Western blotting for GRP78, CHOP and β-actin (A). Densitometric analysis indicates that TM treatment significantly upregulated GRP78 expression. A combined treatment of TM with 4-PBA also resulted in increased GRP78 expression over VEH, but did not show increased expression over TM treatment. 4-PBA alone had no effect on GRP78 expression (B). CHOP expression was increased in response to TM treatment. Co-treatment of TM and 4-PBA resulted in increased CHOP expression, which was significantly higher than VEH treatment, but significantly lower than TM alone treatment. 4-PBA alone-treated cells showed no difference in CHOP expression, when compared with VEH (C). *, P<0.05 vs VEH; ^#, P<0.05 vs TM.