SLCO1B1 and glioblastoma: Previous studies have reported the expression of OATP2 in human microglia, macrophages, monocytes and dendritic cell populations.45,46 Given that high myeloid load correlates with poor patient prognosis in a range of solid tumors, including GBM,26 we investigated the expression of the OATP isoforms in the IBA1+ GBM myeloid populations.