Heterogeneity in Ena and Scar at filopodium tips accompanies exponentially distributed filopodium lengths in vivo. (A–C) Varying intensities of Ena (cyan) at the tips of filopodia (membrane marker expressed using the Gal4 system shown in magenta) in leading edge cells in dorsal closure (A), myotubes (B), and tracheal cells (C) in the Drosophila embryo. Pictures are maximum-intensity projections of the cell marker together with the filopodium tip z-slice of the Ena channel. Scale bars = 2 μm. (D) Time-lapse montages every 15 s of filopodia in leading edge cells in dorsal closure in the Drosophila embryo with fluorescent Ena. Yellow and white arrowheads indicate filopodium tips with and without protein, respectively. Scale bar = 1 µm. (E–H) Similarly, Scar in dorsal closure (E), Ena in myotubes (F), Scar in myotubes (G), Ena in tracheal cells (H), and Scar in tracheal cells (I). (J–L) Scatter plot of maximal (Max.) Ena and Scar intensities at filopodium tips versus maximal end-to-end (straight) filopodia length, respectively, in dorsal closure (n = 53 and 58), tracheal cells (n = 42 and 51), and myotubes (n = 10 and 12). Spearman correlation coefficients and associated P values are shown. (M) Log plots of filopodium lengths from control (n = 150), GFP-Ena (n = 343), and mNeonGreen-Scar/WAVE (n = 213) knock-in homozygous flies are exponentially distributed and largely similar.