PTK2 and breast cancer: NOV enhances migration of chondrosarcoma cells by increasing MMP-13 expression through αvβ3/αvβ5 integrin receptor, FAK, PI3K, Akt, p65, and NF-κB signal transduction pathway and regulates the differentiation of bone resident cells creating a resorptive environment that promotes the formation of osteolytic breast cancer metastases [54], [55].