Fn binding of synchronized CD34⁺ cells via α4 and α5 integrins.

(A) Adhesion to Fn-coated plates was determined in synchronized CD34⁺ cells at indicated stages of the cell cycle. The contribution of α4 or α5 integrin in mediating Fn binding was determined by incubating cells with specific blocking antibodies or control IgG prior to the adhesion assay (n = 4). *Percent adhesion of either IgG- or anti-α4–treated CD34⁺ cells was statistically different between indicated stages. (B) Adhesion of synchronized CD34⁺ cells was determined on whole plasma Fn, α4-binding 40-kDa (Fn40) fragment, or α5-binding 120-kDa (Fn120) fragment (n = 4). *Adhesion to the 40-kDa fragment was significantly lower compared with both whole Fn and the 120-kDa fragment (P < .05).