In general, {HEAD ~ recombinant techniques} involve isolating the genes responsible for coding growth factor, cloning {TAIL ~ the gene} in suitable vectors and cell types, modifying the gene if necessary to encode a desired variant, and expressing the gene in order to produce the growth factor protein product 
In general , { HEAD ~ recombinant techniques } involve isolating the genes responsible for coding growth factor , cloning { TAIL ~ the gene } in suitable vectors and cell types , modifying the gene if necessary to encode a desired variant , and expressing the gene in order to produce the growth factor protein product
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