FN1 and cancer: Invasive cancer cells traveling along the 3D cell-derived matrix of fibrillar collagen and fibronectin (Cukierman et al., 2001) can track the topology of the fibrils with defined lamellipodial and filopodial projections at the cell’s leading edge (Paul et al., 2015a; Caswell and Zech, 2018), similar to cells moving on 2D substrates.