Fig. 4.

Suppression of tunicamycin-induced ER stress by rapamycin. RPTC were treated with 1 μg/ml tunicamycin in the absence or presence of 100 nM rapamycin for 0–24 h as indicated. Cell lysate was collected for immunoblot analysis of p-mTOR, p-PERK, p-eIF2α, CHOP, GRP78, and actin (loading control). A: representative immunoblots. B: densitometric analysis of protein expression. The signal of each protein band was measured by densitometry and then divided by the actin signal in the same sample. Data are expressed as means + SD (n = 3). To show the effect of rapamycin, the protein signals at each time point were compared. *P < 0.05.