Fig. 2. Ventral podosome domains contact the substrate. (A) Typical `late' podosomes are detected both by epifluorescence imaging (A) and TIRF microscopy (A') in GFP--actinin-expressing cells. The TIRF picture shows that -actinin in the ventral podosome domain is distributed in ring-like structures, surrounding the podosome core. (B) Podosomes in A7r5 cells are adhesive structures. Arrows indicate the areas of adhesive contact detected by interference reflection microscopy (B'), corresponding to the podosomes visible in the phase contrast images (B).