Fig. 3
From: Regulation of Transcription Functions of the p53 Tumor Suppressor by the mdm-2 Oncogene
Suppression of p53 transactivation by mdm-2 and mdm-2 mutants
(A) Suppression of p53 transactivation by mdm-2 One microgram of pCOSXl-CAT is cotransfected with indicated amounts of plasmid p11–4 (encoding murine p53) into SAOS-2 cells. Five micrograms of human mdm-2 expression plasmid or pCMV-neo-Bam vector is included in each transfection. CAT activities are shown as percent conversion of substrate. In this experiment, mdm-2 suppressed the transactivation by up to 200 ng of p53 plasmid. (B) Suppression of p53 transactivation by mdm-2 mutants. One microgram of pCOSX1-CAT is cotransfected with 20–50 ng of pC53-SN3 plasmid encoding human p53 and 5 µg of mdm-2 deletion mutant plasmid or vector. The inhibition of transactivation by the mdm-2 mutants are shown as percentage of CAT activity compared with vector. Thus, 100% indicates no suppression, and 20% represents 5-fold suppression. Each mutant was assayed in at least five experiments and the error bars represent standard deviation.