Klp61F knockdown inhibits post-Golgi transport in Drosophila S2 cells. Drosophila S2 cells transformed to stably express ssHRP-V5 were transfected with dsRNAs for LacZ (dsLacZ: control), TANGO1 (dsTANGO1), twinstar (dsTsr), or Klp61F (dsKlp61F). (A) The knockdown efficiency was monitored by RT-PCR. (B) HRP activity in the medium from control, TANGO1, Tsr, and Klp61F knockdown cells was detected by ECL and normalized to the levels detected in the cell lysates. The average values of three independent experiments are shown (mean ± SD). Stars indicate P < 0.005. (C–E) The amount of secreted (C) and intracellular (D) HRP-V5 was measured by Western blotting the medium and the cell lysate with anti-V5 tag antibody. To monitor the amounts of proteins loaded, α-tubulin in the cell lysate was used as a marker. (E) Ratio of the 50-kD (mature form) to 65-kD (immature form) polypeptides of HRP-V5. The average values of three independent experiments are shown (mean ± SD). Stars indicate P < 0.005.