Expression of recombinant glycoproteins carrying the sialyl-Lewis(X) epitope requires host cells equipped with appropriate glycosyltransferases. Chinese hamster ovary cells transfected with tricistronic vectors and encoding the resistance marker gene, neoR, in the third cistron and core 2 N-acetylglucosaminyltransferase or alpha 1,3-fucosyltransferase III or IV in either the first or second cistron, respectively, produced both enzyme activities in a constant ratio. A representative clone was transfected with PSGL-1 (P-selectin glycoprotien ligand 1) and conferred P-selectin-binding activity to PSGL-1.