Increased actin polymerization occurs as an early event during invadopodium maturation. A 10-min time-lapse video of a GFP-actin MTLn3 cell stimulated with EGF showing that barbed ends at invadopodium precursors peak between 1 and 2 min after stimulation with EGF. (green = GFP-actin). Images were acquired every 10 s and movie speed is 7 frames/second.