Myo1b depletion decreases F-actin in filopodia and increases F-actin in the interfilopodial veils. (A) Representative confocal z stacks of cortical neurons expressing control mCherry-shRNA or Myo1b-Cherry-shRNA and mGFP-F-tractin-P. Bars, 11 µm. (B) The fluorescent intensity of F-actin within the area occupied by filopodia has been quantified on all sections of the stacks and normalized to the fluorescent intensity measured on the area occupied by the total growth cone on all sections and represented as box plots. n = 23 or 25 in three independent experiments. Data distribution was assumed to be normal. Unpaired t test. **, P < 0.01. (C) Cortical neurons transfected with plasmid encoding control mCherry-shRNA or Myo1b-mCherry-shRNA (B) were analyzed with SIM. Representative merged images of growth cones showing F-actin (gray) and mCherry (red) are shown. Bars, 5 µm.