Effects of the endogenous TLP and TAp63 in the regulation of DNA damage response. A, siRNA-mediated knockdown of the endogenous TLP and TAp63. Hep3B cells were transiently transfected with 10 nm control siRNA, siRNA against TLP (TLP-1) or with siRNA targeting TAp63 (TAp63-1). Forty-eight hours after transfection, cells were exposed to 50 μm etoposide. Forty-eight hours after etoposide treatment, whole cell lysates were prepared and processed for immunoblotting with indicated antibodies. B, TUNEL staining. Hep3B cells were transiently transfected as in A. Forty-eight hours after transfection, cells were exposed to 50 μm etoposide. Forty-eight hours after etoposide treatment, cells were fixed in 4% parafolmaldeyde and subjected to TUNEL staining. Cell nuclei were stained with 4′,6-diamidino-2-phenylindole (DAPI). The percentage of TUNEL-positive cells shown in each column represents the mean of three independent experiments (right panels).