(A) PERK (Thr980) phosphorylation after 4-PBA (10 mM) treatment for 24 hours in Tsc1−/− MEFs. Phospho-S6K-1 (Thr389), total S6K-1, and phospho-S6 (ser235/236) levels were analyzed with or without 4-PBA treatment in Tsc1−/− MEFs, shown in triplicate. (B) mRNA levels of CHOP, XBP-1s and GRP78 in Tsc1+/+ and in Tsc1−/− cells either in the presence or absence of 4-PBA (10mM) after 24 hours incubation. (C) PERK phosphorylation (Thr980), phospho-S6K-1 (Thr389), and total S6K-1, phospho-S6 (ser235/236) levels with or without 4-PBA treatment in Tsc2−/− (+VEC) MEFs and in their controls Tsc2−/− (+TSC2) cells. (D) CHOP, XBP-1s and GRP78 gene expression levels in WT (+TSC2) and Tsc2−/− (+VEC) cells treated with PBA (10mM) or PBS for 24 hours. Data are mean ± SEM of triplicates.