Silver staining of the SDS-PAGE-separated LOS molecules of the four strains used to affinity purify human IgG, 35E (L2), 1291 (L7 equivalent), 6940 (L1), and 8532V (L8 variant). The LOS were electrophoresed through 27 cm of a 13.1% polyacrylamide gel. The asterisks indicate the position of lacto-N-neotetraose, and the arrowhead indicates the position of L1.