TABLE 3.

Ligand-dependent stimulation of the murine mdm2 p53 response sequence by T3R in p53-null cells^a

Transfection	CAT activityb
	Basal	T3
ΔMTV-m59-CAT	6.6	6.3
+p53	35.9	39.7
+cT3Rα	5.1	20.1
+cT3Rα + p53	10.2	39.4
+hT3Rβ1	6.9	31
+hT3Rβ1 + p53	16.7	48.8

^ap53-null (10)1 cells (67) were transfected by calcium phosphate coprecipitation in 9-cm² wells with (per well) 1.25 μg of ΔMTV-m59-CAT alone or with 0.25 μg of cT3Rα, 0.25 μg of hT3Rβ1, or 0.25 μg of p53 expression vector as indicated. Cells were incubated with and without 500 nM T3 and harvested for determination of CAT activity 48 h later. Cells which were transfected with only p53 also received 0.2 μg of control expression vector which lack the cT3Rα or hT3Rβ1 cDNAs. 

^bPercentage of [¹⁴C]chloramphenicol acetylated per 20 μg of cell protein in 16 h.