HIF1A and osteosarcoma: In the human osteosarcoma cell line MG-63, a hypoxic environment (similar to that typically found in tumors) induces the expression of high amounts of SENP1 [150], and inhibiting SENP1, in turn, reduces the expression of two major hypoxia-induced genes, HIF1α and VEGF (vascular endothelial growth factor).