Schematic representation of ALK3 partitioning within and outside focal adhesions. BMP2 induces ALK3 redistribution at the cell surface into different domains corresponding to two confined populations of ALK3: one is confined to discrete regions, namely FAs, in which BMPRII subunits show no tendency to cluster (left side), and the other is homogeneously immobilized in the plasma membrane outside of FAs, likely through its association with BMPRII (right side). Integrin αVβ3 is an FN receptor that recognizes the tripeptide cell-binding site Arg-Gly-Asp (RGD) located in the FN 7–10 domain. FN acts as a scaffold upon which the bioavailability and activity of several growth factors, including BMP2, is orchestrated through their interaction with the FN 12-14 domain. The close proximity between the integrin-binding and BMP2-binding domains of fibronectin favors proximity between ALK3 and β3 integrin in FAs. Exclusive ALK3 enrichment within FAs requires both BMP2 and integrin engagement to the extracellular matrix. Smad signaling requires ALK3, BMPRII, and β3 integrins (right side), whereas cell adhesive processes (spreading and migration) rely solely on ALK3 and β3 integrins (left side). The asterisk, circle, or square positioned at the intracellular domain of ALK3 indicate a conformational change that might be crucial to expose sites of phosphorylation or provide a docking site for specific kinases or signaling molecules to control ALK3 recruitment outside and within FAs.