AXL and central nervous system cancer: Studies have shown that Axl is upregulated in non-small-cell lung cancer (NSCLC), melanoma, osteosarcoma, acute myelocytic leukaemia (AML), schwannoma, glioma, and thyroid cancer cell lines [6, 22, 34–36] and that Axl is overexpressed in tumour tissues from patients with NSCLC, osteosarcoma, AML, and thyroid cancer [21, 22, 34, 35].