FIG. 7.

Downregulation of hHR23 results in accumulation of endogenous p53. (A) U2OS cells (which express endogenous wt p53) were transfected with an expression construct for HA-tagged hHR23 or with an expression construct for CD44 for control. Twenty-four hours h after transfection, levels of p53, c-Jun, hHR23, or CD44 were determined by immunofluorescence using the anti-p53 antibody CM-1, the anti-c-Jun antibody sc-45, a monoclonal anti-HA antibody, and a monoclonal antibody against CD44. p53 and c-Jun are stained in red. hHR23 and CD44 are stained in green. (B) Primary human fibroblasts were microinjected with an expression vector encoding GFP either alone, in combination with control siRNA, or in combination with siRNAs directed against mRNAs encoding hHR23A and hHR23B. Three days after microinjection, p53 expression was determined by immunofluorescence using the p53-specific antibody DO-1. GFP expression is shown in green, and the p53 protein is stained in red.