Locally concentrating NM2 monomer results in filament assembly. (A) Cartoon of iLID optogenetic system with photo-recruitable NM2 monomers expressed with endogenously tagged NM2. (B) Representative frame of optogenetic recruitment of NM2 monomers in the cell. (B and C) The magenta box indicates the zoom inset region, the orange circle marks the activated region, and the green area shows the direction of retrograde flow. (B and D) Activation, retrograde flow, and control areas shown in orange, green, and yellow, respectively. (C) Time series of optogenetic NM2 recruitment with recruitable NM2 in blue/gray and endogenous NM2 in purple/gray. The left panel is the recruitable NM2, the middle panel is endogenous, and the right panel is an overlay of the two channels. (D) Quantification of the normalized intensity increases (mean ± SD) upon blue light activation (gray box) in the indicated regions. The data represents 19 cells from five experiments.