Complex I is downregulated in angiogenic compared with invasive tumors. (A) Immunostaining for complex I and porin in invasive and angiogenic xenografts. Complex I is downregulated in angiogenic compared with invasive xenografts while porin is not differentially expressed. (B) Western blot with antibodies against HIF1A and VEGF. (C) Immunostaining for complex I and porin in low-grade glioma and GBM. Asterisks indicate necrotic areas.