Fig. 2. (A) Effect of the simultaneous presence of CS chains in the substratum on cell attachment to FN or ConA substratum. The attachment of human IMR90 cells was assessed by the cell attachment assay as described in the Materials and Methods. The wells were coated with 5 µg/ml FN, 8 µg/ml ConA and 5 µg/ml CSPE. +RGD, the addition of 2 mM GRGDSP peptide to medium; +RGE, the addition of 2 mM GRGESP peptide to the medium. (B) Attachment of cells to CSPE substratum via a specific interaction with CS chains. Compared with the attachment to FN, human IMR90 cells weakly but significantly attached to CSPE substratum. +CSase, the pretreatment of the wells with chondroitinase ABC; +CS, the addition of 1 mg/ml CS (shark cartilage) to the medium; +HA, the addition of 1 mg/ml HA to the medium. The addition of CS (whale cartilage) and dermatan sulfate at the same concentration as above had the same inhibitory effect, and chondroitin had no significant effect (data not shown). (C) Dependency of the cell attachment to CSPE substratum on Ca²⁺. IMR 90 cells were plated onto CSPE-coated wells containing the media with variable concentrations of EGTA and Ca²⁺. The results are expressed as mean values and standard deviations of determinations from at least three independent experiments.