For example, loss of negative-regulatory receptor tyrosine kinases Tyro3, Axl, and Mer exacerbates lupus-like disease, rheumatoid arthritis, and inflammatory bowel disease through enhanced Toll-like receptor signaling (Rothlin et al., 2007; Lemke and Rothlin, 2008; Rothlin and Lemke, 2010). Here, AXL is linked to inflammatory bowel disease.