Functionally, OPN expression in the tumour microenvironment is associated with various aspects of progression, including promotion of cell migration, invasion and metastasis, fostering proliferation and tumour growth, enabling tumour cell survival, chemoresistance and stemness properties, induction of epithelial mesenchymal transition, stimulation of angiogenesis and the activation of CAFs, as well as the creation of a tumour-promoting immunosuppressive microenvironment [22,30,31]. Here, SPP1 is linked to neoplasm.