Figure 1

Cyclin A2-rich foci persist until telophase and localise to the cleavage furrow.

(A) Observation of endogenous cyclin A2 foci. MCF-7 cells were treated with bafilomycin A1 (BFA), fixed and immunostained for cyclin A2 and LC3-B. Confocal images. Spectral colocalisation plots of the indicated foci (arrowheads) are shown to the right. Representative images of >50 cells from three independent experiments. Scale bars: 2 μm. (B) Imaging of cyclin A2-EGFP foci. A MCF-7 cell synchronised by single thymidine block, microinjected with pEGFP-N1-cyclin A2 and observed in mitosis 14 h after release. Images obtained by two-photon excitation with a FLIM detector. Green and orange arrows point to distal and furrow foci, respectively. Representative images of >100 cells from three independent experiments. Scale bars: 2 μm. (C,D) Quantification of EGFP intensity in images of 4 cells (103 foci in total) followed during mitosis (as in (B)). The data shown in the graph represent the mean intensity relative to t₀ (prometaphase in (C), metaphase in (D)). Data representative of three independent experiments.