Figure 2.

Visualization of 3A9 cell stopping by antigen and Ca²⁺ mobilization. (Left) Interference reflection microscopy. (Right) Pseudocolor Fura-2 ratio. (Bottom Left) Fluorescence image indicating ICAM-1 secondary bilayer (unlabeled) and ICAM-1 + I-A^k–HEL48–62 containing primary bilayer (labeled). The arrow indicates a cell that crawled from the 800 molecules per μm² ICAM-1 bilayer onto the 800 molecules per μm² ICAM-1 + 20 molecules per μm² I-A^k–HEL48–62 bilayer, stopped at the boundary, and initiated cytoplasmic Ca²⁺ oscillations.