Figure 5.

Live‐cell imaging of blue‐light‐induced metaphase arrest and apoptosis in HeLa cells. Cells treated with 10 μm MG132‐Cage were either exposed to 405 nm LED light for 5 min (top row) or maintained in the dark (bottom row). Merged transmission and confocal mKate‐α‐tubulin (maximum z‐projection shown in green) images for indicated time points are shown. Scale bars represent 20 μm. a) Prometaphase cells exposed to 405 nm light arrested in metaphase (top row). Control cells in the dark entered anaphase and completed cell division (bottom row). Selected time frames are taken from Movie 1 (see Supporting Information). b) First apoptotic cells were observed ≈12 h after 405 nm light exposure (top row). Cells maintained in the dark continued proliferation without undergoing apoptosis (bottom row). Selected time frames are taken from Movie 2 (see Supporting Information). c) Prometaphase cells exposed to 405 nm light arrested in metaphase for 2 h. After washing the cells proliferation continues establishing reversibility of the arrest. After 20 h no signs of apoptosis are seen. Selected time frames are taken from Movie 3 (see Supporting Information).