Label-free observation of cancer-cell filopodium activities using structured illumination nanoprofilometry

We used label-free structured illumination nanoprofilometry to study the activities of cancer-cell filopodia under various external stimulations, including concentration gradients of epidermal growth factor, electric fields, and substrate stiffness. Combined with fluorescence microscopy, we revealed some intracellular molecules that are related to these filopodial responses. We also identify a novel cancer metastasis enhancer which is related to higher degrees of filopodium growth.