L-AA enhances IRE1– c-Jun N-terminal kinase (JNK)–CHOP-mediated cell death. (A) HCC-38 cells were pre-treated with ER stress inhibitors (10 μM of 4μ8C, 1 μM of SP600125, 10 μM of GSK2606414, and 10 μM of Salubrinal) for 1 h, and then treated with L-AA (200 μM) for 48 h. Cell viability was measured using the trypan blue assay. (B,D) HCC-38 cells were transfected with CHOP siRNA. (B) CHOP siRNA-transfected cells were treated with 200 μM of L-AA for 6 h and then western blotting was performed (C) CHOP siRNA-transfected cells were treated with 200 μM of L-AA for 48 h, followed by the trypan blue assay (D) CHOP siRNA-transfected cells were treated with 200 μM of L-AA for 10 days, followed by the colony formation assay. Data are shown as the mean of three independent experiments, and the error bars represent standard deviation (SD). *** p < 0.001 was considered statistically significant.