Expression of ₄, ₅, and β₁-integrins on ICSBP-deficient progenitor cells. (A) Gating of bone marrow cells according to surface expression of c-kit, as measured by FACS. (B) FACS-analysis of ₄- (top panel), ₅- (middle panel), and β₁-integrin (lower panel) expression on c-kit⁺–gated (see A) bone marrow cells from ICSBP^+/+ (left) and ICSBP^−/− (right) mice. Filled histograms represent control traces from cells stained only with FITC-labeled secondary Ig. (C) Adhesion of CFCs to immobilized antiintegrin antibodies. Bone marrow cells from wild-type (black bars) or ICSBP^−/−mice (gray bars) were incubated in 48-well plates precoated with antibodies to the indicated integrins. Adherent cells were subjected to a CFC assay as described in Materials and Methods and in the legend to Fig 5A. Data shown represent mean ± SEM of 2 independent experiments performed in triplicate with 2 mice per group.