ERN1 and neoplasm: However, as compared with massive and well-delineated U87 control tumor bulks, glioblastomas expressing the IRE1α-Y892A mutant were invariably diffuse and harbored two distinct features of invasion: a short-range infiltration at the immediate periphery of glioblastoma cores, and an extensive blood vessel co-option with formation of distal perivascular tumor microsatellites.