Behavior and fate of cell-surface TSP-1 in T lymphocytes. (A) Detection of TSP-1 (Ab4) and TIMP-1 in nonpermeabilized and per-meabilized AF24 cells after 15 minutes on fibronectin (FN) and poly-L-lysine (PLL). It is evident that the control molecule TIMP-1 is not expressed on the cell surface. Arrowheads point to cells. (B-C) RAP (B) and CRT (C) displace TSP-1 and expose CD91. AF24 cells were incubated with RAP (50 μg/mL) or CRT (1 μg/mL) during adhesion to fibronectin, and the cell-surface expression of TSP-1 was determined after 15 minutes. One representative experiment of 3 to 8 independent experiments is shown. Error bars indicate SEM. Statistics: Mann-Whitney U test. Bars: 10 μm.