ROR2 and osteosarcoma: In contrast, ROR2 is overexpressed in several human cancers, including renal cell carcinoma (11, 12), osteosarcoma (10), melanoma (13), stromal tumors (14), as well as breast (15, 16), colorectal (17), oral (18), and pancreatic cancer (19), and has been associated with a more aggressive disease state and poorer patient prognosis within these indications.