Figure 5.

Pair-correlation analysis of an active protrusion tip. (A) The intensity pseudoimage of actin-eGFP at the protrusion tip at orbit 1 and orbit 2 (same position). (B) Pair-correlation of orbit 1 to orbit 2 (G₁₂) and orbit 2 to orbit 1 (G₂₁). Similar to the analysis from a stable protrusion, both correlation functions show long correlation at specific positions, indicated by arrows. (C and D) However, when correlating the intensity of actin-eGFP at the protrusion tip at orbit 1 and orbit 3 (0.5 μm apart), the flow (and its direction) was captured, as can be seen from the prominent peak in G₁₃ (pointed by arrows). At the same location, G₃₁ shows no significant correlation in the opposite direction. (E–H) For the collagen channel, the correlation at orbits at the same position shows long, consistent correlation, whereas the correlation of orbits 0.5 μm apart shows the pattern of flow similar to actin-eGFP nearby (panel H), suggesting the actin flow also changes the collagen position around the protrusion. To see this figure in color, go online.