FLT3 and hepatocellular carcinoma: The progression of HCC tumors significantly initiated by RTKs such as vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), epidermal growth factor receptor (EGFR), fibroblast growth factor receptor (FGFR), hepatocyte growth factor receptor (HGFR/ c-MET), stem cell growth factor receptor (c-KIT), and FMS-like tyrosine kinase 3 (FLT3) [7].