Figure 2.

Annexin II is efficiently recruited to patches of antibody cross-linked CD44 microdomains. EpH4 cells grown at low cell density on coverslips were labeled with anti-CD44 antibody. Control samples (A–C and G–I) were fixed and then stained with secondary goat anti–rat antibody, while experimental samples were treated with secondary anti–rat IgG before fixation, causing in vivo cross-linking of CD44 on the cell surface (D–F and J–L). Control and experimental samples were then counterstained with anti-annexin II antibody (A–F) or anti-caveolin/VIP21 antibody (G–L). In control cells, CD44 (A) and annexin II (B, see merged images in C) were evenly distributed over the entire plasma membrane. Upon antibody cross-linking CD44 as well as annexin II could be found in patch-like clusters on the surface of the cells (D, E, merge see F). In contrast, caveolin/VIP21 was located in larger spots most likely representing caveolae before or after antibody cross-linking of CD44 and failed to colocalize with CD44 in control- (G–I) or cross-linked (J–L) cells. Bar, 10 μM.