Figure 3: Phosphorylation of selected key proteins from five major cell-signalling pathways in primary human liver stellate cells treated with ZnO nanoparticles or dissolved ZnSO4, at 30 μg/mL. Cells were treated in quadruplicate with ZnO nanoparticles, or ZnSO4, for each treatment time-point (0.5, 1, 2, 4, 6, 8, 12 and 24 h). Levels of protein phosphorylation were averaged, and expressed as the percentage of phosphorylation of the same protein in untreated cells set as 100%. The five cell-signalling pathways are: I NFκB (pro-inflammatory signaling); II ATM/ATR (DNA damage signalling); III mTOR (cell metabolism, growth, survival, and proliferation signalling); IV AKT (cell survival, proliferation, and apoptosis signalling); V MAPK (cell growth, survival, and differentiation signalling). The data used to generate this figure, and associated standard errors of means and statistical significance, are supplied separately in Supplementary Table 1.