Fig. 1. GFP-xLBR overexpression leads to nuclear membrane overproduction. (A) Location of GFP-xLBR expression during the cell cycle. HeLa cells were transfected with GFP-xLBR expression vector and visualized under a fluorescence microscope to judge the expression levels of the fusion protein. HeLa cells expressing low levels of full-length GFP-xLBR of various stages of cell cycle were fixed and visualized for GFP or stained with DAPI for DNA. Note that the fusion protein was located to the NE and ER in interphase and had normal cell cycle distribution dynamics. (B) High level expression of GFP-xLBR caused nuclear membrane overproduction. Note that with increasing expression of GFP-xLBR, the excess NE either folded into the nucleoplasm (arrows) and/or formed vesicular aggregates (arrowheads) in the cytoplasm. DNA was stained blue with DAPI. Bars, 10 µm.