FIG. 6.

Lysosomal exocytosis is more rapid in PMCA^mut cells than in parental cells. (A) Cells were incubated with tetramethylrhodamine-coupled dextran (2 mg/ml) for 1 h to load lysosomes with dextran. The cells were then washed and incubated in dextran-free medium for another hour and then treated with TNF. Dextran retention was measured by flow cytometry at the indicated time points after TNF treatment. (B) Parental and PMCA^mut cells were switched to fresh medium and untreated or treated with TNF for 2 h as indicated. Activity of the lysosomal enzyme β-hexosaminidase was measured in the medium and in the cells. The amount of enzyme in the medium is expressed as a percentage of the total enzyme level found in the cells. (C) Cells were treated with A23187 and TNF changes in VAC are shown.