FIG. 4.

Association of p73α with tumor-derived p53 mutants but not wild-type p53. H1299 cells were transfected with an expression plasmid for either wild-type p53 (p53 wt), p53R175H, p53R248W, or p73α, alone and in combination as indicated. p53 was precipitated from extracts (1.5 mg of protein) incubated with 100 ng each of anti-p53 MAbs 240 and 1801. Western blots of the immunoprecipitates (IP) were probed with either the anti-HA antibody 16B12 (upper panel) or the anti-p53 antibody 1801 (lower panel) (see Materials and Methods). The middle panel is a Western blot loaded with 100 μg of extract and probed with the anti-HA antibody to detect p73α.