BspHI restriction analysis of cDNA after RT-PCR of transfected CHO cell mRNA. Total RNA was purified from the transfected cell clones CHO β3-wt, CHO β3-met, and CHO β3-pro; reverse transcribed; and amplified by RT-PCR using specific primers. The amplified cDNA was digested by BspHI, and for each cell clone, undigested and digested cDNA was submitted to acrylamide gel electrophoresis. Lanes 1 and 2, β3-wild-type cDNA fragment of 401 bp before (lane 1) and after (lane 2) BspHI digestion; lanes 3 and 4, β3-met 395-bp cDNA fragment before (lane 3) and after (lane 4) digestion; lanes 5 and 6, β3-pro 395-bp cDNA fragment before (lane 5) and after (lane 6) digestion; lane 7, undigested wild-type β3 cDNA fragment; lane 8, 1-kb DNA ladder (GIBCO).