Cancer cells can produce exosomes full of tumor-promoting signaling molecules, such as Src tyrosine kinase, insulin-like growth factor 1 receptor (IGF-IR), and focal adhesion kinase (FAK) [91] Src, which signals through FAK, has been associated with many aspects of tumor progression, such as cell proliferation, metastasis, and angiogenesis; in addition, Src signaling is known to crosstalk with IGF-IR, which also promotes angiogenesis [91]. Here, PTK2 is linked to cancer.