NGF-deprivation induces caspase-mediated cleavage of actin and tubulin. (a, b) NGF-replete (+NGF) cultured sympathetic neurons are viable and axons are intact, as visible with β3 tubulin (Tuj1) staining. NGF-withdrawal-induced apoptosis causes axon degeneration by 12 hours that is marked with antibodies against cleaved actin (fractin) (a) or TubulinΔCsp6 (cTub) (b) and is suppressed by caspase inhibition using ZVAD. Intensity of fractin (c) and TubulinΔCsp6 (d) staining in axons was measured in arbitrary fluorescence units (a.u.). A diagram of the microfluidic chamber used is shown in (e). Data represents three independent experiments. One-way ANOVA, *p < .05, **p < .01. Scale bar = 10 μm.