CXCL12 and hemangioblastoma: Sporadic and VHL-related hemangioblastomas had the same level of CXCL12 expression (Fig. 2c), with strong expression in 75 % (12 out of 16) of sporadic hemangioblastomas and in 81 % (13 out of 16) of VHL-related hemangioblastoma cells.