IL6 and glioblastoma: For example, the 5-HTR5A was found to be downregulated in GBM compared to low-grade gliomas, and its stimulation enhanced GBM autophagy and apoptosis.22 Conversely, the 5-HTR7A was identified as promoting IL-6 release by U373 GBM cells, thereby facilitating tumoral progression via an autocrine pathway.23 Additionally, 5-HT may modulate the tumor microenvironment, potentially influencing the immune response to tumors.