SG3299 Inhibits Sphere Formation in αvβ6-Expressing Patient-Derived Xenograft PDAC cells. A, αvβ6 (upper panel) and CD133 expression of 354, 253 and 215 PDX PDAC cells using flow cytometry. Isotype control IgG is unshaded and gray shaded peaks represent αvβ6 expression. Lower panel, representative co-expression of CD133 and αvβ6 where the majority of CD133+ cells express αvβ6. Isotype control is shown in black and the stained cell population in blue (n=2-5 replicates). B, Representative images of 354 cell spheres formed after 10 days culture following 3 days pre-treatment with Control (DMSO), NT-peptide SG3511 or SG3299 (1 nM) (X4 magnification, scale bar=500μum). C, Histograms quantifying the sphere formation assay shown in (B) (error bars represent standard deviation, n=5-6 wells/treatment). ***P<0.001 (relative to NT-peptide or SG3511 treatment arm).