Phenotypic analysis of 8226 cell surface FN receptor expression by flow cytometry. Integrin subunit expression by drug-sensitive (8226/S), melphalan-resistant (8226/LR5), and doxorubicin-resistant (8226/DOX6) cell lines were analyzed using MoAbs for ₄, ₅, β₁, and β₇. Cells were incubated with an integrin-specific MoAb (—) or with irrelevant control Ab (---), followed by incubation with FITC-conjugated secondary Ab. Ten thousand events were analyzed for each sample using a FACScan machine (Becton-Dickinson); histograms are representative of three different experiments.