Fig. 3. Determination of the specificity of the RECQL4 antibodies by siRNA. (A) Western blot with anti-RECQL4 C-t antibody (upper panel) or anti-tubulin antibody (lower panel) using total cell extracts from HeLa cells transfected with 200 nM RECQL4-1 or control-1 siRNA. Asterisks indicate breakdown products. (B) RECQL4 knock-down leads to a loss of RECQL4 nuclear foci. Immunofluorescence analysis with anti-RECQL4 N-t antibody (red) on exponentially growing HeLa cells transfected with 200 nM RECQL4-1 or control-1 siRNA, DAPI-staining shows nuclear DNA (blue). Bar, 10 µm. (C) The mean number of RECQL4 foci per cell after siRNA treatment is displayed in histograms (standard error of the mean is indicated in the columns).