Our invention relates to a new way of preparing coding DNA constructs, by making a chimera of various coding region isoforms. For example, our method has been successfully used to make a new hGH-NV cDNA chimera having SEQ ID NO: 3, by combining the cDNA isoforms of human placenta and pituitary RNA encoding human growth hormone. Our invention also relates to a process for increasing the production of recombinant human growth hormone by inserting a plurality of promoter--coding region--termination sequences into a vector in tandem. For example, our method has been successfully used to approximately double the yield of recombinant growth hormone in transformed cells.