NPC density and nuclear growth during interphase. (A) An NRK cell stably expressing Pom121-3EGFP was tracked throughout the entire cell cycle. The signal from NPCs on the bottom surface of the nucleus is shown in inverted grayscale. Times relative to the first observed mitosis are indicated. (B) Individual landmark NPCs were tracked, and the area between them was measured as indicated. Overlay of the measured areas (right) illustrates the overall increase in area during the observation time. (C) NPC density through the cell cycle of individual cells (black). Each curve was fitted with a linear function using the least squares method, and the mean fit is shown in red (gray shading, SD of fit parameters). (D) Growth of nuclear surface area between tracked NPCs (n = 8). The area was normalized to the first time point, and each curve was fitted with a single exponential to derive the mean growth (red; gray shading, 95% confidence interval).