IL1B and glioblastoma: Previous studies investigating the role of IL-1β signaling in in vitro GBM patient-derived primary cell cultures have yielded inconsistent results: some demonstrate no effects on tumor cell proliferation, while others either demonstrate tumoricidal properties of rIL-1β or tumor-promoting properties, all depending on cell culture conditions and time of exposure to rIL-1β (29, 44–49).