For example, expression of alternative splice variants of vascular endothelial growth factor (VEGF-A) has implications for the regulation of angiogenesis [27] and splice variants of receptor tyrosine kinases can lead to auto-active and oncogenic PI3K signaling (e.g. EGFRVIII and METΔ7–8 in glioma and METΔ14 in lung cancer [28–31]). This evidence concerns the gene PIK3CA and central nervous system cancer.