In view of the pronounced cytotoxic activity of Vandetanib in D283 Med and D341 Med, lack of concomitant downregulation of STAT3 phosphorylation indicates that in these cell lines other pathways e.g. mitogen-activated protein kinase pathways as also shown for osteosarcoma might be involved in the integration of oncogenic signals transmitted by Vandetanib target structures [29, 38]. This evidence concerns the gene WNK2 and osteosarcoma.