Lack of evidence of physical interaction between CD44 and CR3 (CD11b/CD18). (A,B) Immunofluorescence images of CD44 (red) CD11b (green) of resting RAW macrophages. (C,D) Overlay and direct interference contrast (DIC) images. (E,F) Immunofluorescence of CD44 (red) and CD11b (green) of CD44 cross-linked RAW macrophages. (G,H) Overlay and DIC images. XL indicates cross-linking. Scale bars represent 5 μm. (I) As determined by Western analysis of CD44 and CD18 immunoprecipitates, no detectable binding of the other molecule was observed in the immune complexes. Images are representative of 3 independent experiments.