Cell migration can sometimes be destructive, which is known as cell invasion. This is defined as the movement of cells through a three-dimensional (3D) matrix, and includes attachment to, as well as degradation and restructuring of the matrix components. Cancer cells often display invasion-type movement through the extracellular matrix (ECM). As such, by mimicking this process in cell-based invasion assays, it is possible to reveal the cell migration mechanisms underlying tumor formation and metastasis, as well as inform the development of novel cancer therapies.