Both KIF9 proteins participate in cell motility, but only KIF9B is involved in PFR assembly. (A) Western blot of total protein samples (10⁷ cells per lane) from noninduced (0 h) and 96 h–induced KIF9A^RNAi cells (left) and KIF9B^RNAi cells (right), with the experiment performed at least three times. The same membrane was cut into three parts and probed with anti-KIF9A antibody (left), anti-KIF9B antibody (right), or L8C4 and MAb25. Values on blot are given in kilodaltons. (B) Sedimentation assay showing the mean of five reproducible experiments. Trypanosomes were incubated in cuvettes, and optical density was measured before and after mixing. KIF9A^RNAi (blue) and KIF9B^RNAi (black) were induced for 4 d or 3 d, respectively (solid lines). Control cells were grown without tetracycline (dashed line). (C) Cumulative growth curves of KIF9A^RNAi and KIF9B^RNAi mutants under noninduced conditions (dashed line) and induced conditions (solid lines), representative of four experiments. (D and E) IFA on 72 h–induced KIF9A^RNAi (D) and KIF9B^RNAi cells (E) performed at least 20 times. Combined phase-contrast and DAPI images (left), MAb25 (middle left), L8C4 (middle right), and combined DAPI, MAb25, and L8C4 images are shown (right).