Effect of the MLL/MEN chimeric protein on p53-dependent transcription. (A) HeLaS3 cells were transfected with 2 μg of 2x RGC-Luc, 2 μg of CMVp53, and 2 μg of pME18S-MEN(HA), pME18S-MLL/MEN(HA), or pME18S-tMLL(HA) by using a calcium phosphate method. The total amounts of the transfected DNAs were equalized in all samples with the backbone vector, pME18S. Equal amounts of the cell lysates were assayed for luciferase activities 24 hours after transfection. The highest value was arbitrarily set as 100 and all others were consequently normalized. (B) HeLaS3 cells were transfected with 2 μg of pXP2-HH0.34, 2 μg of CMVp53, and 2 μg of pME18S-MEN(HA), pME18S-MLL/MEN(HA), or pME18S-tMLL(HA) by using a calcium phosphate method and were assayed in the same way as (A).