Table 2.

Agar colony formation by CEF infected with LEF-1-ER constructs

Infecting construct	Colonies per 104 cells
	No additive	Estrogen	Tamoxifen
Vector (RCAS)	0.68	0.68	0.55
LEF-1	(180)*	(180)*	(180)*
LEF-1-ER	2.0	83	1.7
LEFΔN-ER	0.63	31	0.38
ER	1.3	1.7	1.0

^*Colonies induced by LEF-1 remained very small.