CXCL12 and glioblastoma: The glioblastoma cell lines U251 and DK-MG secreted very few chemokines in 21% O2 cultures, mainly CXCL16, CX3CL1, and CXCL8 for U251 cells and CCL3/4 and CXCL12 for DK-MG cells, and this profile was even lower in 1% OA more extensive profile of secreted chemokines characterized MSCs, but the highest signal indicative of chemokine secretion was found in co-cultures (especially U251 with MSCs).