Ldb1 is required for localization of the β-globin locus away from the nuclear periphery during differentiation. (A) Three-dimensional immuno-FISH analysis of untreated cells and cells treated with DMSO. WT indicates MEL cells; Ctrl KD, MEL cells with control shRNA; KD, MEL cells with shRNA directed to Ldb1; U, uninduced; and 4D, treated with DMSO for 4 days. Red represents nuclear lamin immunofluorescence; and green, probe detecting the β-globin locus. Bar represents 5 μm. For details see “Image acquisition and analysis.” (B) Quantitation of association of globin loci with the nuclear lamina before and after DMSO treatment for 3 days (3d) or 4 days (4d). More than 100 cells were scored for each determination. Error bars represent the SE.