MEG8 and neoplasm: We selected ROR1 as the potential marker gene for tumor cells because MEG8 is a long non‐coding RNA (lncRNA), whereas ROR1 encodes a cell surface receptor closely related to tumor growth, invasion, and metastasis.[36, 37, 38] In addition, we compared the expression levels of ROR1 in other synovial samples and found that ROR1 was rarely expressed in Fbs from OA synovium (Figure S4D, Supporting Information).