SPP1 and neoplasm: This work also demonstrated that intracellular OPN-induced mesenchymal epithelial transition was dependent on miR-429 and AKT1 expression and endothelial PAS domain protein 1 (HIF2α) downregulation, in addition to being pivotal to the establishment of lung metastasis, while in other cancer cell lines that expressed secreted OPN, the secreted OPN induced EMT-related tumor-progression features [65].