Figure 4

Enhancing LSR expression increases iota cytotoxicity while reintroduction of CD44 conveys resistance in LSR^low/CD44^lowcells. SUM1315mo cells were stably transfected with a control plasmid (pCMV), a plasmid containing the full-length gene for LSR variant 1 (LSR+), or a plasmid containing the full-length gene for CD44 variant 1. Cells were grown to 80% confluence; lysates were isolated and analyzed (A) via western blot analysis using a LSR specific antibody and α-tubulin for loading control or by (B) immunofluorescence using CD44- and LSR-specific antibodies. DNA was stained with DAPI. (C) Cells were treated with Ia or Ia + Ib for 8 h in complete growth medium at 37°C. Representative images demonstrate cell rounding and detachment from tissue culture dish, indicative of cell death. (D) Cells death visualized in (C) was quantified at the indicated times via fluorescent cytotoxicity assay. *P < 0.05. A minimum of three independent experiments was performed for each analysis.