Impaired membrane PR3 expression in RBL/PR3 transfected with rPLSCR1/siRNA after etoposide-induced apoptosis. (A) Flow-cytometry analysis after rhodamine-conjugated siRNA electroporation. Typical experiment showing that 85% of the cells emitted a positive signal after siRNA electroporation (bold line), whereas no fluorescence was detected in the absence of siRNA (thin line). (B) Western-blot analysis of rPLSCR1 and FcϵRIβ expressions in RBL/PR3 transfected with control siRNA or rPLSCR1 siRNA. Different amounts of cell lysates (20, 10, or 5 μg) were loaded per well. Most rPLSCR1 protein disappeared 48 hours after electroporation with siRNA but not control siRNA. No FcϵRIβ modulation was observed. (C) Flow-cytometry analysis of membrane PR3 expression (bold line) versus control IgG1 (thin line) of RBL/PR3 transfected with either control siRNA or with rPLSCR1 siRNA after etoposide-induced apoptosis. (D) Flow-cytometry analysis of membrane rPLSCR1 expression (bold line) versus control IgG1 (thin line) of RBL/PR3 transfected with either control siRNA or with rPLSCR1 siRNA after etoposide-induced apoptosis. (E) Decreased PS externalization and membrane PR3 and rPLSCR1 expression after rPLSCR1 siRNA transfection. Percentages of annexin-V labeling and membrane PR3 and rPLSCR1 expression were significantly lower (data are means ± SEM; *P < .05 Student t test, n = 4) for apoptotic RBL/PR3 transfected with rPLSCR1 siRNA than control siRNA.