HTR5A and glioblastoma: The exact role of 5-HT in GBM remains unexplored for several aspects.8 5-HT has been implicated in the modulation of several cancer-related pathways, including PI3K/AKT and MAPK, which are critical for cell survival and proliferation.41 Moreover, various 5-HT receptors are expressed on GBM cells, suggesting that they may influence tumor behavior via receptor-mediated mechanisms.