Attachment VII - Page 11 
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) How is the structure of the added DNA sequences monitored 
and Vvhat is the sensitivity of the analysis? Is the added 
DIPi ext rach r cmosoma 1 or integrated? Is the added DNA 
unrearranged? 
(4) Hew many ccpies are present per cell? How stable is the 
added DNA 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 fran 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 retroviral system is used: 
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