A full length mouse Sox6 cDNA modified to append a human MYC tag to the carboxyl terminus of the protein product was cloned into the pEFneo vector downstream of the human eukaryotic elongation factor 1 alpha 1 promoter. Northern blot analysis using a Socs6 cDNA probe and western blot analysis with an anti-MYC antibody demonstrate that mice of line 2 express transgene-derived mRNA and protein, respectively, at 10-fold the levels expressed by wild-type mice from the endogenous gene in liver, muscle and T-lymphocytes. (J:181312)