Bone Neoplasms/drug therapy; Lung Neoplasms/drug therapy; Osteosarcoma/drug therapy; Proto-Oncogene Proteins c-ret/antagonists & inhibitors; Proto-Oncogene Proteins/antagonists & inhibitors; Receptor Protein-Tyrosine Kinases/antagonists & inhibitors; Receptor, EphB2/antagonists & inhibitors; Receptor, Fibroblast Growth Factor, Type 2/antagonists & inhibitors; Antineoplastic Agents/therapeutic use; Bone Neoplasms/genetics; Bone Neoplasms/metabolism; Bone Neoplasms/pathology; Cell Differentiation/drug effects; Cell Proliferation/drug effects; Gene Expression Regulation, Neoplastic; Humans; Lung Neoplasms/genetics; Lung Neoplasms/metabolism; Lung Neoplasms/secondary; Osteosarcoma/genetics; Osteosarcoma/metabolism; Osteosarcoma/secondary; Protein Kinase Inhibitors/therapeutic use; Proto-Oncogene Proteins/genetics; Proto-Oncogene Proteins/metabolism; Proto-Oncogene Proteins c-ret/genetics; Proto-Oncogene Proteins c-ret/metabolism; RNA, Small Interfering/genetics; RNA, Small Interfering/metabolism; Receptor Protein-Tyrosine Kinases/genetics; Receptor Protein-Tyrosine Kinases/metabolism; Receptor, EphB2/genetics; Receptor, EphB2/metabolism; Receptor, Fibroblast Growth Factor, Type 2/genetics; Receptor, Fibroblast Growth Factor, Type 2/metabolism; Signal Transduction; Axl Receptor Tyrosine Kinase