Regulation of endogenous genes by using DOX-inducible siRNAs. Left panels, downmodulation of p53. MCF-7 cells were infected with the indicated lentivirus vectors as described in Materials and Methods. Western blotting was performed with monoclonal antibodies against p53, GFP, or actin (as a control). Right panels, downmodulation of lamin A/C. The same experiment as for the left panels was performed with HeLa cells, using lamin-specific siRNA vectors and antibodies.