Given that microglia and macrophages have been linked to TGF-β activity in GBMs, we also tested whether simvastatin treatment affected peritumoral macrophages/microglia; immunohistochemistry for the Iba1 marker indicated increased number and extent of Iba1+ cells in the tumor periphery with simvastatin treatment (Supplementary Figure 5A-5B). Here, TGFB1 is linked to neoplasm.