NRP1 and cancer: Additionally, substrate stiffness is known to regulate the expression of genes related to cancer progression, including the growth factor VEGF165, one of the ligands of NRP1 (Sack et al., 2016), and some integrins such as α5β4 (Schrader et al., 2011), which, when overexpressed and bound to NRP1, promote ECM remodeling, induce tumor growth, and contribute to desmoplasia and stiffening in tumors (Yaqoob et al., 2012).