Other growth factors that have been associated with the pathogenesis of meningiomas include: 1) the stromal cell-derived factor 1 (SDF1) CXC chemokine and its CXCR4 receptor, which might exert its mitogenic effects through the MAPK pathway [62]; 2) the bone morphogenic proteins (BMPs) and their receptors (BMPR), which are associated with Smad 1 signaling, and; 3) the fibroblast growth factor (FGF) and its FGFR3 receptor, which are activated by the PI3K/Akt pathway [63]. This evidence concerns the gene AKT1 and meningioma.