HPLC analysis of DMB-sialic acid. Sialic acid was released by mild acid hydrolysis, derivatized with DMB, and separated by HPLC using the elution condition described in “Materials and methods”. The elution positions of DMB-labeled standard NeuAc and NeuGc, and sialic acid derived from C57BL/6 lympnodes, parental CHO cells expressing NeuAc (CHO-NeuAc) and transfected CHO cells expressing NeuGc (CHO-NeuGc) are shown in a, b, c, d, and e, respectively. CHO cells expressing NeuAc and NeuGc are designated CHO/PSGL/ C2/F7 and CHO/PSGL/C2/F7/Cmah, respectively (Fig. 5)