Fig. 4

Induction of cellular stress responses by LNCs. a Schematic overview of potential cellular stress responses that may be induced by LNCs. The integrated stress response can be triggered by the four kinases GCN2, HRI, PERK and PKR, and be a result of oxidative stress, ER stress, amino acid starvation, unfolded/misfolded proteins, or viral RNA. b Cell lysates were prepared from MCF-7 (top), MDA-MB-231 (middle) and MDA-MB-468 (bottom) cells treated with 0.5 mg/ml of LNCs at 37 °C for the indicated time periods. The blots were probed with the indicated antibodies and representative blots are shown. c Immunoblots of cell lysates prepared from MCF-7 (top), MDA-MB-231 (middle) and MDA-MB-468 cells (bottom) treated at 37 °C for 8 h with the indicated concentrations of LNCs. d HAP1 WT, ΔGCN2, ΔHRI, ΔPERK and ΔPKR cells were treated with 0.5 mg/ml of LNCs for up to 4 h at 37 °C followed by immunoblotting of the cell lysates. One representative experiment is shown. e Quantification of data from four independent experiments like the one shown in d. The ratio of p-eIF2α to total eIF2α was normalized to the untreated control cells. Data show mean values ± SEM, *p < 0.05