Schematic of MT exclusion upon optogenetically induced cross-linking. EB1 (yellow) tracks and recruits EGFP-SKIP-LZ-iLID to the growing MT plus end. CH-CH-tgRFP-SspB engages F-actin. Upon blue light activation, the iLID module engages CH-CH-tgRFP-SspB, cross-linking MTs and F-actin. In the F-actin–rich peripheral zone, the F-actin density and/or retrograde flow drives MT plus end exclusion from the region and “sweeps” MT comets along the peripheral zone boundary.