FIGURE 4.

PIPP regulates axon formation and elongation. A, hippocampal neurons were transfected with PIPP or scrambled siRNA and stained with Tau-1 antibodies. Arrowheads indicate Tau1 positive neurites. Bar = 40 μm. B, cells transfected as in A were stained with Tau-1 antibodies and scored for none, single, or multiple Tau-1+ve neurites per cell. C, cells transfected as in A were stained with phalloidin. Arrowheads indicate the longest neurite in each cell. Inverted grayscale images are shown. Bar = 40 μm. D, neurite length of cells treated as in C were measured. Bars = mean length (μm) ± S.E. (20 cells, n = 3, *, p < 0.05). E, cells transfected as in A were stained with β-tubulin antibodies and presented in graded fluorescence. Bar = 20 μm. F, the mean tubulin fluorescence intensity in neurites in cells treated as in E. Bars = mean ± S.E. (20 cells, n = 4, *, p < 0.05). Bars = mean ± S.E. (20 cells, n = 3, **, p < 0.01).