PDGFRB and mast cell neoplasm: The therapeutic relevance of PDGFRβ in canine cancers is further supported by the efficacy of treatment with RTK inhibitors (TKIs) such as toceranib phosphate, which targets PDGFRβ among other kinases, for various canine malignancies [19], including mast cell tumors [20], osteosarcoma, and thyroid carcinoma [20].