TABLE 1.

Colony formation when SFME cells are transfected with T antigen or mutants of T antigen and subjected to selection in the absence of EGF and in the presence of G418

DNAa	No. of colonies obtained		No. of colonies expressing proteind	No. of colonies growing without EGFe
	Without EGFb	With G418c
T antigen	15	20	5	5
N136	20	31	10	10
3213	0	14	8	0
N136–3213	0	26	3	0
1135	0	15	6	0
1137–1135	0	12	5	0
5110	0	18	7	0
PKO-NEO	0	30		0

^aThis column indicates the plasmid that was transfected into the cell. PKO-NEO is a G418 resistance plasmid. 

^bNumber of colonies obtained after transfected cells were placed in medium that did not contain EGF. 

^cNumber of colonies obtained when transfected cells were placed in medium containing G418. 

^dSubset of colonies from the G418 selection that were examined for T-antigen expression. 

^eNumber of T-antigen colonies that were able to grow in the absence of EGF.