(A) Typical Western blots showing the activation of ER stress markers, (p-elF2α, p-IRE, BiP), JNK and ERK in HL-1 cells 30 min after PLY treatment. (B) Representative western blots showing the effect of PLY on the induction of apoptotic markers CHOP and active caspase-3 after 8 hour of treatment. Thapsigargin (Tg 5 μM) and Staurosporin (Stau 10 μM) were used as positive inducers of CHOP and active caspase-3 respectively. (C-G) Effects of PLY (1.0 μg/ml) and PLY+ 4-Phenylbutyric acid (4-PBA, an ER stress inhibitor, 10 mM) on Peak Shortening (C), (+dL/dt) (D), TTP (E), tR90 (F) and (-dL/dt) (G) of HL-1 cells after 30 min treatment are presented as Mean±SD (n = 9 from 3 independent experiments). * p<0.05.