Salubrinal may restrict growth by increasing expression of CHOP and suppressing cyclin D1 levels. (A) Western blots for total ErbB2, phospho-Ser473 and total Akt levels after 24 hr salubrinal treatment (10 μg/ml) of cells grown in monolayer conditions. GAPDH was used as loading control. (B) G raph showing quantification of the percentage of CHOP positive cells per acinus, mean ± SEM. Statistical significance was determined using the unpaired t-test with p < 0.05 defined as statistically significant. N.S - not significant. Note the modest increase in CHOP expression in salubrinal-treated vector control and Wt-ErbB2 acini but not in CA-ErbB2 acini. (C) Western blots (top panels) for cyclin D1 levels after 72 hr salubrinal treatment (10 μg/ml)of cells grown in monolayer conditions. GAPDH was used as loading control, N.S-non-specific band. Bottom graph, Cyclin D1 protein levels were quantified by scanning densitometry and normalized to GAPDH.(D) Schematic depicting the growth-inhibitory effects of increased eIF2α phosphorylation on aberrant acinar morphogenesis induced by ErbB2.