Fig. 3. Silencing of endogenous Rab3A, Rab27A, and Rab33A with specific siRNAs. PC12 whole-cell lysates were prepared 2 days after transfection with Rab3A-siRNA (A), Rab27A-siRNA (C) or Rab33A-siRNA (E) as described in Materials and Methods. The knockdown effect of the siRNAs on endogenous expression of Rabs was evaluated by immunoblot analysis with specific antibodies (see also Fig. 2). The positions of the molecular mass markers (x10^-3) are shown on the left. (B) PC12 cells transiently co-transfected with pEGFP-C1 and with a control vector (a-c) or with a vector containing Rab3A-siRNA (d-f). (D) PC12 cells transiently co-transfected with pEGFP-C1 and with a control vector (a-c) or with a vector containing Rab27A-siRNA (d-f). (F) PC12 cells transiently co-transfected with pEGFP-C1 and with a control vector (a-c) or with a vector containing Rab33A-siRNA (d-f). Note that expression of the specific siRNAs dramatically reduced endogenous expression of the Rab proteins (see arrowheads in panel e of B,D,F). Bars, 10 µm.