Figure 2. Functional effects of R77H in K562 cells.

K562 cells lacking β₂ integrins (--), or stably expressing α_M^WT or α_M^R77H with β₂ were evaluated for adhesion to iC3b and ICAM-1 following activation with Mn²⁺ or Mg²⁺/EGTA, under static conditions or flow conditions. (A) Adhesion of α_M^WT or α_M^R77H cells to iC3b-coated surfaces under static conditions. Results are presented as percent of adherent cells relative to cells expressing α_M^WT plus Mn²⁺. n=6 experiments. (B) Adhesion of α_M^WT or α_M^R77H cells to iC3b and ICAM-1 under shear flow (0.38 dynes/cm²) evaluated at the indicated time points. Results are presented as percent of adherent cells relative to cells expressing α_M^WT at 8min. n=3–4 independent experiments. (C–D) Binding of α_M^WT- cells to ligand-coated surfaces following treatment with indicated β-propeller antibodies (as in Figure 1) under static (C) or shear flow (D) conditions. (E) Cell adhesion under shear flow in cells expressing α_M^WT or α_M^R77H with β₂^WT or β₂^V124A. (F–G) Adhesion of α_M^WT or α_M^R77H cells pretreated with leukoadherin-1 (LA-1) or vehicle control (F) or CBR LFA1/2 or control antibody, CBR LFA1/7 (G). (H) Adhesion of cells expressing α_M^WT or α_M^R77H with or without a GFFKR deletion (Δ). n=3 for panels E–H. **p<0.01, ***p<0.001. See also Figure S2, S3 and Table S1.