Schematic illustration of the micropatterning method to graft microtubules seeds (green) via neutravidin (yellow) and actin-nucleation-promoting complexes (orange) on 8-micron-wide discoidal micropatterns. A glass coverslip (deep blue) coated with polyethyleneglycol (PEG) (light blue) was placed in contact with a transparency mask and exposed to deep UV light. The exposed coverslip was then immersed with neutravidin to fix biotinylated microtubule seeds (green) on exposed regions. Streptavidin-WA was immobilized on microtubule seeds via their interaction with biotin. Tubulin dimers and actin monomers were then added to allow filaments elongation. 