Figure 6.

Btk expression overcomes Wortmannin inhibition on H₂O₂- but not B cell receptor-induced Ca^{2 +} mobilization. Fura-2-loaded DT40 (A, C, and E) and DT40 overexpressing Btk (B, D, and F) were washed and then suspended in HBSS buffer (A–D) or calcium-free Hanks' balanced salt solution buffer containing EGTA (E and F). Cells were preincubated with DMSO vehicle (0.06%) or 100 nM Wortmannin in DMSO for 10 min and then stimulated with 5 mM H₂O₂ or 2 μg/ml of α-IgM. Arrows and arrowheads indicate the start of stimulation or the addition of calcium chloride (final concentration 1.3 mM), respectively.