Distribution of Myo1b in cultured cortical neurons. (A) After 1, 3, 5, and 8 d of culture, lysates of cortical neurons were analyzed by SDS-PAGE and immunoblotting with anti-Myo1b antibodies. GAPDH was used as a loading control. (B) The amount of Myo1b detected in the lysates has been quantified as described in Materials and methods and expressed as AU. Data are shown as the mean of three experiments. Error bars represent ± SEM. (C) Cortical neurons DIV2 were immunolabeled with anti-Myo1b and anti–β3-tubulin antibodies, fluorescently labeled for F-actin with phalloidin, and analyzed by confocal microscopy. A representative overlay of z stack for F-actin (red), Myo1b (green), and β3-tubulin (magenta), and the independent z stack for Myo1b are shown for cortical neurons at stage 2 and stage 3. Bars, 20 µm. (D) Cortical neurons DIV2 immunolabeled with anti-Myo1b and anti–β3-tubulin antibodies and fluorescently labeled with phalloidin were analyzed by SIM. Representative images of the growth cones of one short and one long neurite labeled for Myo1b and its overlay (green) with the corresponding image for β3-tubulin (magenta) and phalloidin (red) are shown. Bars, 5 µm.