Fig. 4

Apoptosis by DAT1 upon blocking ERK activation a. Cells were treated with DAT1 in the presence or absence of the MEK inhibitor U0126. Subsequently, they were fixed and stained with DAPI and imaged in a fluorescence microscope. Percentage of apoptosis was calculated and plotted as given in Fig. 1. *** denotes p ≤ 0.001 and indicates that the difference between the percentage of apoptosis caused by DAT1 in presence and absence of the inhibitor is extremely significant. b Cells were treated with DAT1 for 24 h with or without the presence of the MEK inhibitor and cell lysates were collected. Caspase 3 assay was performed according to manufacturer’s instructions and analysed as given in the methods section. ** for p ≤ 0.01 and indicates significant difference in the fluorescence intensities arising due to caspase 3 activation in the presence and absence of the inhibitor. c. ERK was inhibited by siRNA against ERK, followed by DAPI staining in the presence or absence of DAT1 and the percentage of apoptosis was calculated and plotted. d,e. Lack of DR5 activation upon blocking ERK activation was checked by western blotting. Indicated cell lines were treated with DAT1 for a period of 18 h in the presence or absence of the inhibitor (d) or in the presence or absence of ERK siRNA (e)