MERTK and rheumatoid arthritis: In sharp contrast, specific alternatively activated M2-like MΦ-related markers, which were prominently upregulated by sCD83 in osteoclast cultures derived from healthy donors, were no longer upregulated in RA patient-derived samples (i. e., Mrc1, Cd36, Mertk, Mrc2, Msr1, and Il-10).