Wild-type human p53 and a series of p53 point mutants isolated from Burkitt's lymphoma (BL) cell lines were tested for their ability to inhibit DNA synthesis in a p53-negative BL cell line and to bind and be degraded by the human papillomavirus type 16 E6 protein. All the mutants lost the wild-type ability to inhibit DNA synthesis, demonstrating that they are all functionally altered. Binding to E6 and consequent degradation of the p53 mutants frequently correlated with changed suppressor properties in BL cells.