LPAR1 and osteosarcoma: a. Activating mutations;b. LPAR1 was mutated in human lung, neuroblastoma, and liver cancers.a. Activating mutations;b. LPAR2 was mutated in human colon cancers;a. Activating mutations;b. LPAR3 was mutated in human melanoma cells and osteosarcoma cells.a. Activating mutations;b. LPAR6 was mutated in human melanocarcinoma.