Fig. 3.

TRAIL-mediated Ca²⁺ release by RyR regulates TRAIL–DR endocytosis and apoptosis in MDA-MB-231 cells. (A) The effect of TRAIL on cell viability in control, BAPTA-AM (10 µM) and EGTA (1 mM) -treated cells. Cell viability after cells are pretreated or not with (B) XesC, an IP3R inhibitor (20 µM), or (C) with different concentrations of Ry, a RyR inhibitor, followed by TRAIL incubation. (D) TRAIL induced caspase-3/7 activation in the presence or absence of 40 µM Ry. (E) FLAG-tag TRAIL uptake in control and Ry pretreated cells. (F) TfnR uptake in control and Ry pretreated cells. Internalization rates were calculated relative to surface bound TfnR or FLAG-tag TRAIL. All of the results are mean values ± SD (n = 3). Two-tailed Student’s t tests were used to assess statistical significance. *P < 0.05, ***P < 0.0005.