FIG. 5.

Phosphorylation regulates localization of SATB1 to PML NBs. (A) MCF-7 cells expressing exogenous EGFP-SATB1(1-202) were treated with calyculin A or calphostin C and then fixed and stained with anti-PML. The fluorescent signals from 100 cells were analyzed (repeated in three separate studies) with an upright confocal microscope to identify cells with SATB1 localized to PML NBs. Representative paired images of PML (red) and SATB1 (green) and the merged images are shown. Control was untreated cells. Bar, 10 μm. (B) Jurkat cells expressing low levels of exogenous SUMO-1 (top panel) were examined by confocal microscopy, as described previously (64). MCF-7 cells expressing EGFP-SATB1(1-202) with specific residues mutated were fixed and stained with anti-PML and examined by confocal microscopy. (C) MCF-7 cells transiently expressing EGFP-SATB1(1-202), wild-type or mutant form, were examined by confocal microscopy. (D) One hundred cells (repeated in three separate experiments) were examined for localization of EGFP-SATB1(1-202) into nuclear dots. The percentage of cells displaying the dotted pattern was graphed for each mutant. The Roman numerals correspond to sections of panel C.