Figure 4. Analysis of RECQ4 variants in chicken DT40 cells (clone #19) containing a conditional RECQ4 mutation.

A. Western blotting analysis using anti-RECQ4 antibodies of DT40 extracts from cells grown with (+) or without (−) doxycycline. Note that expression of the transgene (FLAG-RECQ4) is repressed by doxycycline but the transfected YFP-RECQ4 is not. B. Quantification of cell number 72 hours after addition of doxycycline (+) or mock treated (−). Three independent clones for each of the mutant RECQ4 variants (ΔFL or ΔID1) are shown, together with the average of the three (ALL). Error bars represent SD from at least three independent experiments. C. Direct fluorescence analysis of cells expressing no human RECQ4 (top panel), YFP-RECQ4 (middle) or YFP-RECQ4-ΔID1 (bottom). Note the localization of the YFP proteins to the nucleus, as shown by DAPI staining of DNA.