TLR2 and glioblastoma: Studies have successfully used all-trans-retinoic acid (ATRA), molecules that upregulate cAMP production, bone morphogenic protein 4 (BMP4), and most recently Pam3CSK4, a synthetic Toll-like receptor 2 (TLR2) ligand to differentiate GBM cells [14,15,16,17,18,19].