Apoptosis is a controlled cell-death process mediated inter alia by proteins of the Bcl-2 family. Some proteins previously shown to promote the apoptotic process were found to have non-apoptotic functions as well. Microglia, the resident immune cells of the central nervous system, respond to brain derangements by becoming activated to contend with the brain damage. Activated microglia can also undergo activation-induced cell death. Previous studies have addressed the role of core apoptotic proteins in the death process, but whether or not these proteins also play a role in the activation process has not been reported. Here we explore the effect of the BH3-only protein Bid on the immunological features of microglia by subjecting both WT and Bid deficient primary neonatal microglial cultures to LPS treatment (100 ng/ml, 3h) or left untreated (control) and analyzing their transcription profiles in order to study the role of Bid.