Down-regulation of nucleolin interferes with translocation of endogenous S100A11. (A) HaCaT cells treated with BLM for 30 min or control cells were transfected with specific siRNA for depletion of nucleolin (nucleolin siRNA) or, as a control, unspecific nonsilencing siRNA (control siRNA), respectively. Cells were analyzed by laser scanning confocal microscopy using specific antibodies against S100A11 and nucleolin. (B) Quantification of the nuclear localization of endogenous S100A11 in human HaCaT keratinocytes transfected with a specific nucleolin siRNA or, as control, an unspecific control siRNA. Transfected cells were treated with BLM for 30 min and the relative fluorescence intensity (RFI) of the S100A11 signal in selected areas (2 μm diameter) was assessed in several nuclear areas by a specific anti-S100A11 antibody as well as in untreated cells. At least 25 cells were analyzed for each condition. Data are displayed as mean values (±SD). The average of the S100A11 fluorescence intensities measured in untreated control cells transfected with control siRNA was set as 100%.