Figure 4: Apoptosis pathway activity in HMEECs exposed to FA. (a, b) Cytochrome oxidase activity decreased after 4 h of FA exposure and increased after 24 h of FA exposure in a dose-dependent manner. (c) Caspase-9/Mch6/Apaf-3 activity, measured as the relative absorbance, increased in cells stimulated for 4 h with 1.5 and 2 mM FA. (d) Caspase-Glo 3/7 activity, measured as relative luminescence, decreased after 4 h of FA exposure but increased after 24 h of exposure to FA. Error bars represent the SDs of the mean. The data represent the averages (a, b) or means ± SD (c, d) of three experiments, each with six replicates. compared with control.