Cell migration requires actin/myosin-mediated membrane protrusion of a pseudopodium (or lamellipodium) and its attachment to the substratum. This process guides the direction of cell movement through cytoskeletal remodeling and is regulated by complex signaling networks that act spatially downstream of integrin adhesion receptors. Understanding how these regulatory networks are organized in migratory cells is important for many physiological and pathological processes, including wound healing, immune function, and cancer metastasis. Here, we describe methods for the immunoaffinity purification of phosphotyrosine proteins (pY) from pseudopodia that have been isolated from migratory cells. These methods are compatible with current mass spectrometry-based protein identification technologies and can be utilized for the large-scale identification of the pseudopodium pY proteome in various migratory cell lines, including primary and cancer cells.
