Downregulation of PDPN in glioma cells expressing oncogenic EGFR. (A) Derivation of U87 and U373 families of isogenic glioma cell lines driven by EGFRvIII-dependent and -independent pathways of tumorigenesis. (B) Downregulation of PDPN mRNA and protein in U87 and U373 cell lines engineered to express oncogenic EGFRvIII (n = 3). (C) Expression levels of wild-type (WT) (upper band) EGFR, EGFRvIII (lower band), PDPN, and TF in isogenic variants of U373 glioma (n = 2). (D) Immunohistochemical staining for PDPN of glioma xenografts originating from intracranial injection of tumorigenic variants of U373 cells with (U373vIII) or without (U373-PT) EGFRvIII expression (magnification ×100). EGFRvIII-associated downregulation of PDPN is maintained in vivo (n = 6). (E) Reciprocal changes in the expression of EGFR and PDPN in proneural GSC lines (GSC157 and GSC1079) in stem cell (GSC) and differentiated (DIFF) cultures maintained in the presence of serum for 25 to 30 days (n = 3).