Fig. 2. (A) Cell-cycle dependency of nuclear pore distribution in HeLaS3 cells. Nuclei were co-stained for nuclear pores (center column) and PCNA (top panels) or G2 marker CENP-F (bottom panels). The paired nuclei without PCNA signal, probably in G1 phase, possess large pore-lacking islands (top panels, small arrows), whereas the nucleus with early-S PCNA foci (large arrows) has a smaller pore-free island. The two nuclei with large and few PCNA foci (top panels, arrowheads), characteristics of mid-late S-phase nuclei, have a much more uniform pore distribution. The nucleus with CENP-F signal has uniform pore distributions (bottom panels, arrowheads). Nuclei without CENP-F have large pore-free islands on the nuclear surface. Asynchronous cells were used in these experiments. (B) Dispersal of pore-free island with cell-cycle progression. Synchronized mitotic HeLaS3 cells were collected and released at 0 hour. After 3, 6, 9, 12, 15, 18, 21, 24 hours, the number of nuclei in which more than 30% of the surface is comprised of pore-free islands, was counted and shown as a percentage. Cell-cycle profiles of the released cells at the indicated time-points were obtained with an Olympus LCS2, demonstrating cell-cycle progress in a time-dependent manner (histograms).