TABLE 1.

Effects of flanking sequence deletions on IES excision

Injected plasmid	No. of transformed lines showing excision	Total Neor transformed lines	% Excisiona
pIES-NEO	8	10	80
pIES-72	13	15	87
pIES-31	2	10	20
pIES-18	6	14	43
pIES-1	0	15	0

^aCalculated by taking the number of transformed cell lines that contain some spliced 28-bp IES and dividing by the total number of transformed lines. Transformed lines showing excision varied in the amount of spliced product (10 to 100%).