Attachment II - Page 11 
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and after treatment? What is the theoretical and practical 
basis for assuming that only the treated cells will act as 
recipients? 
(2) Is the delivery system efficient? What percentage of the 
target cells contain the added DNA? 
(3) Ho/ is the structure of the added DNA sequences monitored 
and vvhat is the sensitivity of the analysis? Is the added 
Db&. ext rach rcmosoma 1 or integrated? Is the added DNA 
unrearranged? 
(4) How many copies are present per cell? Hew stable is the 
added DtPi both in terms of its continued presence and its 
structural stability? 
b. Laboratory studies of gene expression 
Is the added gene expressed? To what extent is expression 
only from the desired gene (and not from the surrounding DNA)? 
In what percentage of cells does expression from added DNA occur? 
Is the product biologically active? What percentage of normal 
activity results from the inserted gene? Is the gene expressed 
in cells other than the target cells? If so, to what extent? 
c. Laboratory studies pertaining to the safety of the delivery/ 
expression system 
(1) If a retrcviral system is used: 
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