Figure 3.

Mutation of the hyaluronic acid (HA) binding site in CD44 ectodomain sensitizes osteosarcoma cells to doxorubicin. Cd44-positive wild-type cells, Cd44-negative cells, and cells with reconstituted expression of a mutant of CD44 unable to bind HA (Cd44s-R78S-Y79F) were seeded at 60% confluency in DMEM medium supplemented with 7% FBS. The cells were incubated for 24 h with pure solvents (controls) or 1.5 µM DOX and then subjected to immunoblot. The histograms in (A,B) show mean values of MDR1 or cleaved PAPR1 protein levels ± SD from four independent experiments. The values were normalized to loading control. Student’s t-test values: n.s.: p > 0.05, ***: p ≤ 0.001, ****: p ≤ 0.0001. Representative immunoblot is shown in (C).