FLT1 and osteosarcoma: Pazopanib molecular targets (c-KIT-CD117, FGFR2-3 PDGFRα-β, VEGFR-1-2, and -3) displayed a plasma membrane heterogeneous degree of expression in seven osteosarcoma cell lines (Figure 1A), with FGFR2, VEGFR3, and PDGFRβ represented most.