AXL and glioblastoma: In the case of GBM, immune-related cells in tumor microenvironment, such as tumor- associated microglia and macrophages, secrete PROS1 to promote the growth of glioma cells, which phosphorylates and activates AXL in glioma stem cells, thus inhibition of AXL could significantly improve the efficacy of Navurizumab [23].