Fig 3.
Expression of the membrane-proximal GFFKR motif of the α-integrin tail confers enhanced chemoresistance in an adhesion-independent manner. (A, top) Schematic of additional fusion constructs that express the extracellular and transmembrane domains of the carrier epitope Tac, in comparison with α4 and α4δ. Tacδ and Tacδscr are fusions of Tac with the cytoplasmic peptide, KLGFFKR, and the scrambled version, KLRFGFK, respectively. (Bottom) Flow cytometry determination of cell surface Tac and integrin-β1 expression in JB4, JB4-Tacδ, and JB4-Tacδscr cells. Numbers under the histogram are the MFI (scale, 0.1×). (B) JB4, JB4-α4, JB4-α4δ, JB4-Tacδ, and JB4-Tacδscr cells were plated on GST-coated dishes and treated with 0.03 μg/ml doxorubicin for 48 h. Data plotted are the percentage of cells that were apoptotic, based on flow cytometry determination of Cy5-annexin V binding (means ± standard deviations; n = 3). *, P < 0.03; **, P < 0.01.