FIGURE 1:

Collagen/β1 integrin reduces intracellular amounts of doxorubicin. Jurkat (A) and HSB2 (B) cells were preactivated or not with collagen (Col) for 4 h and then treated with 250 ng/ml doxorubicin (Dox) for an additional 2 h at 37°C in the dark. The cells were then washed with PBS, and the intracellular doxorubicin content was analyzed by flow cytometry using the FL-2 settings. Top, flow cytometric profile of intracellular doxorubicin content (NT, nontreated; cells that had not been treated with doxorubicin). Intracellular doxorubicin content (bottom) was quantified according to the following formula: positive cells (%) times mean fluorescence intensity (MFI). (C) Jurkat cells were pretreated with 10 μg/ml anti-β1 (anti-β1 mAb) or IgG isotypic control antibody (control mAb) for 1 h before being activated with collagen. The cells were then treated with doxorubicin, and intracellular doxorubicin amount was determined as described. The results presented in A and B (bottom) and in C represent mean values ± SD from three independent experiments. *p < 0.05 where indicated.