Figure 2

FRAP to determine exchange of PML isoforms at nuclear bodies. (A) FRAP experiment of GFP-tagged PML II in 3T3-PML^+/+ cells. Fluorescence was bleached in circled areas containing a nuclear body as indicated. Image stacks of the whole nucleus were taken before (pre) and after (post) the bleach pulse and at different time points thereafter. The upper row shows the projection of the whole nucleus while the bottom row shows an enlarged view of the bleached nuclear body indicated by a white box. (B and C) Same experiment as in (A) using 3T3-PML^-/- cells. In one cell population fluorescence recovery was observed with kinetics similar to PML wild type cells (B) while in another fraction of cells no recovery of GFP-PML II at nuclear bodies was oberved (C). Bar, 5 μm.