Impairment of actin polymerization causes rapid iEAAR/bundle structure collapse and cell contraction. Related to Fig. 9 F. Cells were cotransfected with GFP-actin and mCherry-MRCKα 1–478 and, after iEAAR assembly, treated with 1 µM latrunculin A, 3 µM cytochalasin D, or cotreated with 100 µM blebbistatin and 3 µM cytochalasin D. Block of actin polymerization causes sudden shortening of bundles and cell collapse. This collapse is mediated by myosin contraction and is impaired by the simultaneous inhibition of myosin.
