Process formation results from the imbalance between motor-mediated forces

Several reports have suggested that neurite outgrowth is mediated by opposi ng forces generated on microtubules and microfilaments but the molecular ba sis underlying these forces have not been determined. Here, we show that in non-neuronal cell lines, the inhibition of actomyosin activity by acidic c alponin promotes the formation of processes. This effect is blocked by inhi bition of the motor activity of cytoplasmic dynein. Therefore, neurite form ation is due to an imbalance between tensile and compressive forces mediate d by myosins and dyneins, respectively. We. propose a mechanism that involv es the motor-mediated forces in a tight regulation of the process formation .