Abstract: More effectively controlled expression of DNA sequences in coding desired heterologous proteins is achieved in differentiated eucaryotic cells by methods of this invention. Disclosed herein are control modules derived from selectively expressed genes of eucaryotic cells, such as, for example, insulin and chymotrypsin genes. These control elements contain cis-acting sequences which are responsive to indigenous trans-acting substances in the differentiated cell, which substances control the expression of the gene. Such cis-acting elements occur within the promoter region of such selectively expressed genes, and also in the five prime flanking region of the coding sequence in a position upstream of the promoter. These upstream enhancer sequences may be located using the methods disclosed herein, and ligated into differentiative expression modules for production of desired heterologous proteins.