Figure 6.

Induction of apoptosis by Dkk-1 does not cause loss of directional polarity. (A) rDkk-1 dose-dependently induced caspase-3 activation in migrating Caco-2 cells after 1 h. (B) The number of apoptotic cells at the leading edge after 24 h was determined by counting of pyknotic nuclei. *p < 0.01; **p < 0.05 versus control. (C) Directional orientation of migrating IEC treated with buffer of rDkk-1 (100 ng/ml) was assessed by MTOC localization (white pseudocolor). Images were taken after 24 h of migration. Inhibition of caspase activation by zVAD-fmk did not attenuate loss of directional polarization. A single M30-positive apoptotic cell (green) can be seen on the right. Nuclei are shown in blue. Arrow heads indicate orientation of cells. Bars, 20 μm.