Figure 4

SMURF1 is associated with CD44 surface expression in sphere-derived cells (SDCs). (A) Flow cytometry analysis of SDCs showing a positive correlation (qualitatively represented by the grey arrow) between CD44 cell surface and intracellular SMURF1 protein expression. Cells were co-stained with fluorescently labeled anti-CD44 (APC) and anti-SMURF1 (Pacific Blue) and the total population is shown. Isotype staining control is shown in B. (B) Gating strategy used to define the CD44^high (top ~10%) and CD44^low (lower ~10%) SDC populations. (C) Histograms of SMURF1 expression in CD44^low and CD44^high populations based on the gates drawn in B. The data shown are representative of at least three repeats for each cell line (TR146, left column; SCC-58, middle column; UMSCC-17B, right column).