Figure 8. ERas cells undergo caspase 3- and caspase 8-regulated apoptosis upon MEK/ERK inhibition. ERas cells undergo caspase 3- and caspase 8-regulated apoptosis upon MEK/ERK inhibition. (A) 2% agarose gel-electrophoresis of DNA fragments extracted from cells after exposure to inhibitors shows apoptotic nucleosomal DNA fragmentation in senescent cells with suppressed MEK/ERK. Cells were treated with inhibitors for indicated time or left untreated and processed to electrophoresis. DNA visualized with ethidium bromide. DNA fragments extracted from serum-starved ERas cells undergoing apoptosis were used as a positive control. (B) Graphical representation of data on caspase 3, 9 and 8 activities after treatment with inhibitors. At the indicated times caspase 3 and 8 activities were measured using Ac-DEVD-AMC for caspase-3, Ac-VETD-AMC for caspase 8 and Ac-LEHD-AFC for caspase 9 fluorogenic substrates at proper wavelengths. Data are presented as mean ±S.E.M. of three independent replicates (n=3).