SFRP1 and glioma: Conversely, in both cell lines, the SFRP1 gene is upregulated, and it has been shown that increased expression of this gene can increase apoptosis in human U251 glioma cells (48), in immortalized human osteoblasts (49), and it has been demonstrated that its strong upregulation can lead to a mitochondria-dependent apoptotic pathway, leading to cytochrome c release (50).