FIG. 1.

In the U2OS cell line, Tax and the Tax mutant M22 inhibit p53 transactivation but the Tax mutant M47 does not. Cells were transfected by the calcium phosphate method with 1 μg of pC53-C1N; 1 μg of pCMV4/Tax, pcTaxM22, or pcTaxM47; and 1 μg of PG13-Luc, and Bluescript (pBC SK−) was used to normalize the amount of transfected DNA in the different samples. To ensure that relatively equal levels of transfection occurred in the different samples, Western blotting was performed for both p53 and Tax. A representative experiment is shown. The arrowheads indicate endogenous p53.