MAP1B is required for the stabilization of invadopodia. (A) Immunoblotting of MAP1B-LC1 in MAP1B siRNA-based KD MDA-MB-231, BT549, and Hs578T cells. (B) Cortactin/actin-positive invadopodia in MAP1B KD cells. Left: Representative immunofluorescence images. Right: Quantification of cells with cortactin/actin-positive invadopodia. Mock and both KD cells, n = 3 experiments. (C) Extracellular gelatin degradation assay of MAP1B KD cells. Left: Representative immunofluorescence images. Right: Quantification of cells with extracellular gelatin degradation. Mock and both KD cells, n = 3 experiments. (D) Quantification of cells with cortactin/actin-positive invadopodia in other TNCB cell lines, BT549 and Hs578T, with MAP1B KD. n = 4 experiments. (E) Quantification of cells with extracellular gelatin degradation in other TNCB cell lines, BT549 and Hs578T, with MAP1B KD. n = 4 experiments. (F) Time-lapse sequences of invadopodia-like structures in MDA/cortactin-GFP stable cells with MAP1B KD. Left: Representative images. Right: Quantification of lifetimes of the cortactin-GFP invadopodia-like structures. Mock, n = 31 dots from eight experiments; KD, n = 31 dots from five experiments. (B–F) The values indicate the mean ± SEM. (B–E) P-values were determined using one-way ANOVA with Dunnett’s (B and C) or Sidak’s (D and E) multiple comparison test. (F) The P-value was determined using an unpaired two-tailed Student’s t test. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001. (B, C, and F) Scale bars, 10 μm. Source data are available for this figure: SourceData F3.