Knockdown of myosin II in OL-DRG cocultures enhances myelin formation. (A) 3-wk-old myelinating OL-DRG cocultures stained for MBP, Olig2, and neurofilament. Cocultures were infected with a lentiviral vector expressing shRNA against the regulatory chain of myosin II (shMLC) or nontargeting scrambled sequence (shSCR). Knockdown of MLC in OPC-DRG cocultures resulted in a significant increase in myelination similar to that observed in cultures treated with blebbistatin. Myelination in control cultures infected with vector alone or in cultures where neurons were preinfected with lentivirus was comparable to that observed in nontreated control culture (not depicted). Bars, 50 μm. (B) Quantitation of MBP⁺ segments per field. Data represent mean ± SEM from two independent experiments (three cultures per condition per experiment).