Reactivity of WT and βTD mutant CD11b/CD18 with genu extension–dependent mAb KIM127. FACS analysis of the reactivity of mAb KIM127 with WT and mutant CD11b/CD18-expressing K562 cells. Level of CD11b/CD18 surface expression was analyzed using mAb IB4. MFI values for mAb staining are shown in each panel from a representative experiment (1 of 3 performed), except that mean fluorescence intensity of KIM127 staining is shown after subtraction of the background mock fluorescence staining levels and after normalization to the IB4 expression values. No binding was observed with isotype control mAb (not shown).