Figure 4. Requirement of UNC119a for the phosphorylation and midbody localization of ERK. (A) UNC119a siRNA treatment inhibits the phosphorylation of ERK. HeLa cells were treated with UNC119a siRNA (siUNC119a) or control siRNA (siN.C) and lysed with RIPA buffer. Western blotting was performed with the indicated antibodies. (B) UNC119a siRNA treatment inhibits the midbody localization of ERK. At 72 h after the siRNA treatment, cells were fixed with paraformaldehyde, permeabilized and immunostained with ERK2-Ab (left panels) or phosphor-ERK1/2-Ab (right panels). In control cells (siN.C), both antibodies bound to the intercellular bridge. Neither antibody bound to the elongated intercellular bridges in UNC119a siRNA-treated cells (siUNC119). Black arrows (DIC images) and white arrows (fluorescent images) indicate the midbody. Insets, higher magnification image of midbodies indicated by arrows. Bar, 20 μm. (C) SFK activity is required for the midbody localization of UNC119a. HeLa cells were treated with PP2 (10 μM), fixed with cold methanol and immunostained with UNC-Ab. Arrows indicate the midbody. Bar, 20 μm.